Sendyne SFP101EVB Datasheet V1

1Preliminary Rev 1.0 © 2014 Sendyne Corp.

Sendyne® Sensing Products Family

Sendyne SFP101EVB

DescriptionThe Sendyne SFP101EVB is an assembled circuit

board module that contains the SFP101 IC, support

circuits required for exercising all of the options and

functions of the IC, and a permanently-attached

(mechanically as well as electrically) 100-µΩ resistive

shunt.

The module simultaneously measures bi-directional

DC current through the shunt, voltage, and tempera-

ture at four points as well as provides separate charge,

discharge and total coulomb counters. The SFP101

provide user-definable automatic compensation for

resistance dependence of the shunt on temperature.

This means that the SFP101 can work with a shunt

of essentially any resistance made from any material,

though the standard board uses a 100-µΩ resistive

shunt.

The module typically achieves an accuracy of

±0.05 % for current measurement over the whole

operating temperature range of –40 °C to +125 °C. It

provides on-board calibration for both current and

voltage, and is programmable to accommodate shunts

with an output voltage from ±10 mV to

±300 mV. Communication is achieved via a LIN-like

serial interface.

The complete evaluation kit for the SFP101EVB also

includes a Serial-to-USB cable, as well as

Sendyne’s SFP101EVB control software, a Windows-

based application.

Features ― Turnkey solution for use in the field

― Typically achieves ±0.05 % accuracy of current

measurement

― Accurate voltage measurement (±0.05 % typ.) with

flexible range

― Accurate temperature measurements at 4 points

― User-definable automatic compensation for

resistance dependence of the shunt on temperature

– Programmable to accommodate shunts with output

voltage from ±10 mV to ±300 mV

― Built-in calibration for current measurements

― Built-in calibration for voltage measurements

― Temperature reporting in degrees Celsius

― Separate Charge, Discharge, and Total coulomb

counters

― Simple serial communication interface

― Automotive temperature range of

–40 °C to +125 °C

― Low power consumption

― “High” or “Low” side current sensing and voltage

sensing reference point with isolated front end

― Windows-based control software provided to

exercise all functions of the board

Applications ― Battery monitoring for industrial, automotive,

railroad and utility scale storage

― Uninterruptible power supplies

― Photovoltaic arrays

― Current flow precision metering

― Drive controls

Sendyne SFP101EVB

Information furnished by Sendyne is believed to be accurate and reliable. However, no responsibility is assumed by Sendyne for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Sendyne. Trademarks and registered trademarks are the property of their respective owners.

Sendyne Corp.250 West Broadway New York, NY 10013, USA [email protected] www.sendyne.com ©2014 Sendyne Corp. All rights reserved.

2 Preliminary Rev 1.0 © 2014 Sendyne Corp.

Sendyne SFP101EVB

Quick Start

Steps in the process1. Plug the 6-pin connector on the FTDI cable onto the

6-pin header connector J2 on the SFP101EVB mod-

ule. Connectors must be aligned as shown in

Fig. 1, black wire on the cable connector and triangu-

lar legend on PCB indicate pin 1.

(Optional) Insert the lead wires of the external therm-

istor (included) into connector J3, at the positions/

terminals labeled TH+ and TH- (see Fig. 2), and se-

cure by tightening the screws. The polarity of the wires

does not matter. This step requires a 2 mm or smaller

flat head screwdriver (not included). The external

temperature sensor will not work without

this step.

2. Plug the USB side of the FTDI cable in the computer

you will be using. Windows should auto detect the

drivers and install them for this device. If not, go to

http://www.ftdichip.com/Drivers/D2XX.htm and

download the latest drivers for your Windows

operating system.

3. Download the SFP101 Control Software from

http://www.sendyne.com/products/SFP101evb.html

and install it.

4. Open the SFP101 Control software. Select the serial

number of the FTDI cable attached to your SFP101

evaluation board from Comm -> COM port. If the

cable is not plugged in or the drivers aren’t installed,

the software will give an error message.

(Optional) Select your desired data acquisition

period/frequency (default value = 200 ms / 5 Hz) and

baud rate (default value = 19.2 kBd). Some baud rates

may not be selectable with some polling frequencies.

(Optional) On the new SFP101, certain calibration

parameters are disabled by default. It is necessary to

enable them to obtain accurate measurements. Click

on the Settings button, go to the Shunt tab, click on

the Enable Internal Shunt Calibration check box if it

isn’t checked.

If your board has a Resistance Temperature Com-

pensation Table uploaded, click on the Enable RTDT

Correction check box. Also in the Voltage tab, click on

the Enable Internal Voltage Calibration check box if it

isn’t checked.

5. Click on the Start button to begin reading data from

the SFP101. Clicking on the graph buttons for each

sensor will bring up the real-time graph of its mea-

surements.

Figure 1: Attachment of the FTDI Cable

Figure 2: Connecting the External Thermistor

pin 1

pin 1


Sendyne SFP101EVB

Using the SFP101EVB

External Connections of the ModuleThe SFP101EVB provides a number of connectors for

links to the circuit being measured and to the Host

controller (or PC), namely, connector J2 (6-pin single-

row 100-mil spacing header with 25x25 mil posts,

see Fig. 4) allows attachment of the Serial-to-USB

cable that provides communications to and from the

module, as well as the operating power; please see the

table below.

Host Connector J2

Pin Number Name Comments1 GND Power return and

logic reference for

digital signals

2 nCTS Clear-to-Send

(active-low)

shorted to pin 6 nRTS;

no other connection in

SFP101EVB Module

3 VCC Power source,

+5.0 V ±10 % (from

Serial-to-USB cable)

4 TxD CMOS-levels Serial

Data Input on the

SFP101EVB

Module, output

from Serial-to-USB

cable

5 RxD CMOS-levels Serial

Data Output on the

SFP101EVB

Module, input on

Serial- to-USB cable

6 nRTS Ready-to-Send

(active-low)

shorted to

pin 2 nCTS; no other

connection in

SFP101EVB Module

Pin 1 of J2 is indicated by a triangle on the PCB silk-

screen legend, and by the square shape of the pad.

Corresponding pin 1 on the Serial-to-USB cable is in-

dicated by a triangular indentation on the body of the

connector as well as BLACK wire connected to

pin 1; please see Fig. 3.

Attention! Please assure that pin 1 on the Serial-to-

USB cable is properly matched to pin 1 on J2.

Figure 3: Connector and Color Coding on the

USB-to-Serial Cable

Pin 1 GND Pin 2 nCTS Pin 3 VCC Pin 4 TxD Pin 5 RxD Pin 6 nRTS


Sendyne SFP101EVB

Connector J3 (4-position miniature screw-terminal

block with 100-mil spacing) provides electrical con-

nections for sensing external voltage and the external

thermistor as described in the following table.

External Sensing Connector J3

Pin Number Name Comments1 VX Voltage to be measured

(in reference to

ISOGND), ~1.05 MΩ

input impedance to

ISOGND

2 ISOGND Isolated GND, the same

voltage potential as

shunt’s mechanical

attachment joint nearest

to Negative Terminal

3 TH- Connection for external

Negative Temperature

Coefficient (NTC)

thermistor, 10 kΩ

1 % at 25 ºC

4 TH+ Connection for

external Negative

Temperature Coefficient

(NTC) thermistor, 10 kΩ

1 % at 25 ºC

Connector J6 carries spare and Factory-Use-Only

signals; please keep all open / not connected.

PowerIf used with a PC, the USB-to-Serial cable carries

+5 V supplied by the USB port to power the

SFP101EVB module.

The SFP101EVB incorporates galvanic isolation

between the Power / Communications signals and

ground potential present on connector J2, and all

measurement signals (shunt terminals for current

sensing, voltage sensing inputs, and thermistors’

sensing). Therefore, the module can be used for “high”

or “low” side current sensing, even when plugged into

a computer.

Current SensingThe resistive shunt provides two holes on its extremes

for attachment of heavy-gauge wires terminated in

compression connectors / lugs; ¼ inch or

6-millimeter bolts should be used for securing the

wires’ connectors to the shunt. Care should be taken

so that the wires do not impress heavy mechanical

load or vibrations on the shunt.

The SFP101EVB is rated for ±100 A continuous cur-

rent (in still air at room temperature); for various

permitted short-time over-current conditions, please

consult the Electrical Specifications on page 11.

Voltage SensingThe voltage sensing input Vx is provided in connector

J3, a miniature screw-terminal block. The reference

/ negative input of the voltage sensing circuit is also

provided on J3 (GND); it is the same as and electri-

cally connected to the negative terminal of the shunt.

The voltage sensing input is rated for continuous

operations with applied potentials up to ±150 V; for

various permitted short-time over-voltage conditions,

please consult the Electrical Specifications on page 13.


Sendyne SFP101EVB

Temperature SensingSFP101EVB incorporates three on-board thermistors

that measure the temperature of the shunt’s active

area at three independent points. The module also

provides the measurement circuit for general-purpose

external thermistor.

All thermistors are rated to operate within and mea-

sure the temperatures from -40 °C to +125 °C, please

consult the Electrical Specifications on page 14 for

details.

The shunt-sensing on-board thermistors are built into

the board and located underneath the shunt; they

are thermally coupled to the bottom of the shunt via

thin, soft, and electrically-isolating thermal interface

material.

The external thermistor is connected to the TH+ and

TH- terminals on the connector J3, a miniature screw-

terminal block. The polarity of this thermistor’s leads

is immaterial.

Control SoftwareDetailed information on the use, features, and speci-

fications of the Sendyne’s control software for the

SFP101EVB is located on page 62 of this document.

Figure 4: Elements of the SFP101EVB


Sendyne SFP101EVB

Contents

1 Sendyne SFP101EVB1 Description1 Features1 Applications2 Quick Start2 Steps in the process3 Using the SFP101EVB3 External Connections of the Module4 Power4 Current Sensing4 Voltage Sensing5 Temperature Sensing5 Control Software10 Functional Block Diagram11 General Description12 Electrical Specifications16 Notes for Electrical Specifications17 Measured Performance Data20 Procedural Notes for Measured Performance Data20 Current and Voltage Offset Tests20 Current Magnitude Error Test21 Voltage Magnitude Error Test22 Absolute Maximum Ratings23 Functionality Overview23 Current Measurements with the SFP101 23 Resistive Current Shunt24 Dual-channel 24-bit ΣΔ ADC25 Reduction of Errors25 Continuous Calibration25 Anti-aliasing and RFI/EMI Filter25 Uncompensated Joints26 “High” and “Low” Side Measurements26 Analog Switches26 Coulomb Counting27 Shunt Calibration28 Shunt Thermal Compensation29 Current Measurement Reporting30 Coulomb Counting Reporting

31 Voltage Measurements with the SFP101 32 Voltage Measurements’ Calibration33 Voltage Measurement Reporting35 Temperature Measurements with the SFP101 39 Temperature Measurement Reporting40 Temperature Reporting in Degrees Celsius41 Support Circuit Implementation41 EMI/RFI Filters41 Drivers41 Isolated DC/DC Converter42 Power Conditioning and Filtering42 Logical Level Shifters and Isolated Communications44 Communications44 Serial Interface44 Baud Rate Selection44 Cyclic Redundancy Check CRC-844 Register Addressing44 Register Groups44 General Purpose Registers

44 Current Acquisition Related Registers

44 Voltage Acquisition Related Registers

44 Temperature Acquisition Related

Registers

45 Message Frames45 Frame Header45 Communications With a Host45 Write Registers46 Read Registers46 Read and Write Multiple Registers46 Communication Errors 46 CRC-8 error

46 Non-existing address

46 Mismatch between transfer type

and accompanying data

46 Address boundary violation

46 Timeout

46 Failure to read back baud rate register

46 Performance & Timeout


Sendyne SFP101EVB

46 Inter-byte space

47 Intra-frame response space

47 ADC Sampling Rate and Data Read-Out47 Data Averaging for Current

and Voltage

47 Data Averaging for Temperatures

48 Access to Flash Tables51 Registers52 General Purpose Registers52 General Purpose Status52 Communication Control52 Reset IC and Write/Erase Control for FLASH Tables53 PNS1: 6-Byte (48-bit) Part Number

String153 PNS2: 6-Byte (48-bit) Part Number String253 SerNo: 24-bit Serial Number53 Manufacturing Code (Addresses 0x21-0x23)53 Part Number (Addresses 0x24-0x25)53 Version Code (Address 0x26-0x27)53 F_DATA: 32-bit FLASH Table Entry 54 F_ENTRY: FLASH Entry Number54 F_TABLE: FLASH Table Number54 F_ERASE: FLASH Erase Register55 Current Measurement Registers56 ADC Current Calibration for Zero Offset56 CUR_OUT: Current Measurement Data Output Registers56 CUR_ACC: Coulomb Counting Data Accumulator56 SHNT_CAL: Shunt Calibration Data57 CUR_GAIN: Current Gain Control57 COMP_CTRL: Compensation Control58 C_TRESH: Charge Threshold Value58 D_TRESH: Discharge Threshold Value58 Voltage Measurement Registers

58 VOLT_OUT: Voltage Measurement Data Output Registers59 VOLT_CAL: Voltage Calibration Data59 VOLT_GCC: Gain & Calibration Control59 Temperature Measurement Registers60 TEMP0_R_OUT: Remote Temperature Measurement Registers60 TEMP1_OB_OUT: Onboard

Thermistor 1 Registers60 TEMP2_OB_OUT: Onboard

Thermistor 2 Registers60 TEMP3_OB_OUT: Onboard

Thermistor 3 Registers61 TEMP0_R_C: Remote Sensor Celsius Data61 TEMP1_OB_C: Onboard Thermistor 1 Celsius Data61 TEMP2_OB_C: Onboard Thermistor 2 Celsius Data61 TEMP3_OB_C: Onboard Thermistor 3 Celsius Data62 Accumulated Charge and Discharge Data62 CHARGE_ACC: 64-bit Accumulated Charge Value62 DIS_ACC: 64-bit Accumulated Discharge Value63 Software Features and Operations65 Viewing Settings65 Viewing Previously Logged Graphs65 Software Elements65 Main Screen65 Menus65 File

65 Logging

66 Comm/Acq

66 Graphs

66 Help


Sendyne SFP101EVB

66 Settings Window66 Tabs

66 Control Registers

66 Data Registers

66 Read Only Registers

66 Non-Volatile Registers

66 Operating Parameters

67 Description of Settings’ Tabs67 General Purpose Tab

67 CommuniCations RegisteR

67 PoweR and Reset RegisteR

67 PaRt numbeR Code, manufaCtuRing Code, and VeRsion Code RegisteRs

67 PaRt numbeR stRing RegisteR

67 seRial numbeR RegisteR

68 Current Tab

68 CuRRent ContRol RegisteR

68 CuRRent data RegisteR

68 Coulomb Counting, ChaRge, and disChaRge data RegisteRs

68 thReshold RegisteRs

69 Shunt Tab

69 CuRRent gain ContRol RegisteR and full sCale adC inPut setting

69 shunt PaRameteR adjustment

69 shunt CalibRation data RegisteR

69 ComPensation ContRol RegisteR 70 Voltage Tab

70 Voltage ContRol RegisteR

70 Voltage data RegisteR

70 exteRnal ResistanCe on Voltage inPut setting

70 Voltage CalibRation data RegisteR

70 Voltage gain and CalibRation RegisteR

71 Temperature Tab

71 temPeRatuRe ContRol RegisteR

71 Remote temPeRatuRe RegisteRs

71 on boaRd temPeRatuRe 1/2/3 RegisteRs

72 Graph Window72 Real Time Graph Display

73 Replay Graph Window74 Mechanical Drawing75 Schematics, Page 176 Schematics, Page 277 Schematics, Page 378 Ordering78 Ordering Information79 Revision History


Sendyne SFP101EVB

This page intentionally left blank


Sendyne SFP101EVB

Functional Block Diagram

Figure 5: Functional Block Diagram

GREF

G

G

×1

×1

×1

x1

CURRENTSENSING

VOLTAGESENSING

TEMPERATURESENSING

ADC1

ADC2

t

AVDD

AVDD

AGND

t

SW SW SW

t t

VX

Calibration Controls

ThermistorSelectionControls

V-XREF

AGND

SHUNT+

SHUNT -

REMOTETHERMISTOR

ON-BOARDTHERMISTORS

CONTROL LOGIC

SERIAL TO USBCABLE (CMOS-LEVEL)

COMMUNICATIONLOGIC

Tx

DVDD

AVDD

Rx

LP FILTER(EMI)

& CALIBRATION

CIRCUIT

VREF

LEVELSHIFT

VREG

FILTER

ISOLATEDDC/DC

GALVANICISOLATION

The circuit and its operation are patented and patent pending

AGND

SFP101


Sendyne SFP101EVB

General Description

The SFP101EVB is an assembled circuit board module

that contains the SFP101 IC, support circuits required

for exercising all of the options and functions of the

IC, and a permanently-attached (mechanically as well

as electrically) 100-µΩ resistive shunt.

The complete evaluation kit for the SFP101EVB also

includes a Serial-to-USB cable, as well as quick-start

instructions for obtaining supporting software and

operating the SFP101EVB with a PC.

Sendyne’s SFP101EVB control software, a Windows-

based application, is employed in conjunction with the

SFP101EVB. It provides visual indication of all mea-

sured values, both in digital-meter and chart formats,

as well as automatic saving of all data in files (data

logging). Furthermore, it allows review and control of

all internal registers and settings for the SFP101 IC.


Sendyne SFP101EVB

Electrical Specifications

All specifications apply over the full ambient operating temperature range, TA = -40 °C to +125 °C, unless otherwise

noted. Supply voltage VCC is 5.0 V ±10 %.


Parameter Min Typ Max Units Conditions/Comments

Power and GeneralTA

Ambient Operating and Storage

Temperature

-40 +125 °C SFP101EVB assembly only NOTE1 (USB

Interface Cable excluded)

TIOCBL

Operating and Storage Tem-

perature of the Serial-to-USB

interface cable

-40 +85 °C Serial-to-USB Interface cable is normally

plugged into a Host PC typically located

in a human-habitable environment that

is much narrower than TIOCBL NOTE2

VCC

Supply Voltage

4.5 5.0 5.5 V Supplied by Serial-to-USB Interface

cable from Host PC

IVCC

Supply Current

16.4 mA 16.4 mA × 5.0 V = 82 mW Typical

TPON

Start-up time

0.5 0.75 s After initial application of power and

power supply stabilization; internal

start-up delay before communications

with SFP101EVB are first allowed

Current Measurement Through negative and positive terminals of the shunt

RSH

Total Shunt Resistance

95 100 105 µΩ As measured between Negative and

Positive terminals (i.e. 100 µΩ ± 5 %)

RSH-SENSE

Shunt Current-sensing

Resistance

73 µΩ Effective current-sensing resistance

between voltage-drop sensing leads

ISH-NOM

Nominal Full-scale current

±100 A Continuous rating at room temperature

(23 °C) in an open environment without

forced air movement. Current is sup-

plied by 1/0 AWG copper cables termi-

nated with appropriate crimp connectors

and attached to the shunt’s Negative and

Positive terminals with threaded fasten-

ers (i.e. bolt + nut) incorporating lock-

washer or Belleville spring to maintain

pressure during temperature changes


Sendyne SFP101EVB



ISH-TEMP

Temporary Full-scale current

±200 A Less than 30 minutes duration, the same

conditions as above for ISH-NOM, initial

shunt temperature is 23 °C

ISH-PK

Peak Full-scale current

±513 A Less than 10 s duration, the same condi-

tions as above for ISH-TEMP. Maximum

current value measured and reported

without clipping or distortionNOTE8

ISH-TRANS

Transient over-current

±3 kA Physical survival rating, less than 5 s

duration, the same conditions as above

for ISH-TEMP NOTE3

ISH-OFST

Current offset error

-3 ±1 +3 mA ISH = 0 A, uncalibrated performance,

applies over the full ambient operating

temperature range,

TA = -40 °C to +125 °C

ISH-ERR

Current value error

-0.4 +0.3 % ISH = 20 A, calibrated at a single (room)

temperature, applies over the full ambi-

ent operating temperature range,

TA = -40 °C to +125 °C NOTE4

ISH-TLM-ERR

Current value error for limited

temperature range

-0.1 ±0.05 +0.1 % ISH = 20 A, calibrated at a single (room)

temperature, applies over TA = +10 °C to

+50 °C NOTE4

ISH-NOISE

Current measurement noise

1.125 1.5 mARMS 1 Hz current report rate. IC is uncali-

brated. Measured over full temperature

range of TA = -40 °C to +125 °C over 18

hours

ISH-COUNT

Current measurement

resolution

61.19 µA Minimum discernible current change;

corresponds to one count of Analog to

Digital Converter (ADC), any current

report rateNOTE8

CSH-COUNT

Charge measurement

resolution

76.49 nC Minimum discernible amount of charge

change; corresponds to one count

change of the accumulated charge value

in the CUR_ACC registersNOTE8


Sendyne SFP101EVB



Voltage Measurement Pins J3-1 & J3-2 (J3-2 is at same potential as the Negative Terminal of the Shunt)

VX-NOM

Nominal Full-scale voltage

range

±150 V Input voltage divider of 1 MΩ / 4.99 kΩ

VX-MAX

Maximum input voltage

±241 V Maximum voltage value measured and

reported without clipping or distortion

VX-MAX -OVLD

Short time maximum input

voltage overload

-300 +300 V Short duration of overload, 5 s maxi-

mum

VX-OFST

Voltage offset error

-20 +10 mV VX = 0 V, applies over the full ambient

operating temperature range,

TA = -40 °C to +125 °C NOTE5

VX-TLIM-OFST

Voltage offset error for limited

temperature range

-5 ±2.5 +5 mV VX = 0 V, applies over TA = +10 °C to

+50 °C

VX-ERR

Voltage value error

-0.1 +0.6 % VX = 25 V, applies over the full ambient

operating temperature range,

TA = -40 °C to +125 °C NOTE6

VX-CAL-ERR

Voltage value error with single-

temperature calibration for

limited temperature range

-0.1 ±0.05 +0.1 % VX = 25 V, applies over TA = +10 °C to

+50 °C. The voltage value is calibrated at

+25 °C NOTE7

VX-NOISE

Voltage measurement noise

225 600 µVRMS 1 Hz voltage report rate. IC is

uncalibrated. Measured over full

temperature range of TA = -40 °C to

+125 °C over 18 hours.

VX-COUNT

Voltage measurement

resolution

28.8 µV Minimum discernible voltage change;

corresponds to one count of Analog to

Digital Converter (ADC), voltage report

rate of 10 Hz or lower


Sendyne SFP101EVB



Temp. Measurements External Thermistor connected to J3-3 & J3-4, and three on-board Thermistors

TERROR

Absolute temperature

measurement error

-1 ±0.5 +1 °C Remote and onboard thermistors, inclu-

sive of measurement noise

TDIF-ERR

Differential temperature

measurement error

±10 m°C Remote and onboard thermistors, for

small changes in temperature

TMATCH-OB

Temperature measurement

matching, onboard thermistors

-0.5 ±0.25 +0.5 °C Between three onboard thermistors

thermally coupled to current shunt

TRES

Temperature measurement

resolution

0.5 m°C Practical temperature measurement

granularity for remote thermistor

RTH

Thermistors’ nominal

resistance

10.0 kΩ ±1 % at 25 °C, all thermistors

RREF

Reference resistance

9.99 10.00 10.01 kΩ For onboard thermistors: R19,

for remote thermistor R8 and 2x R7


Sendyne SFP101EVB

Notes for Electrical SpecificationsNOTE1 The plastic body (pin strip spacing/positioning)

of connector J2 (6-pin single-row 100-mil spacing

header) is only rated for operations within -25 °C to

+105 °C; however, mechanical integrity is assured by

connector pins soldered to plated-through holes in the

PCB; extensive thermal cycling and testing of the

SFP101EVB assemblies have not revealed any in-

stances of connector malfunction. The same consid-

erations apply to connector J3 (4-position miniature

screw-terminal block with 100-mil spacing).

NOTE2 If operations of the SFP101EVB outside of the

USB I/O cable temperature range are required, an

appropriately-rated extension cable should be utilized

between the end of the I/O cable and connector J2 on

the SFP101EVB assembly; the entire USB I/O cable

must be located in the environment that complies with

TIOCBL specification.

NOTE3 Applications of transient over-currents of maxi-

mum amplitude are decisively discouraged as the

shunt’s resistance may shift as much as ±0.5 %.

NOTE4 Effectively, parameters ISH-ERR and ISH-TLM-ERR

characterize performance of the resistive shunt only;

error contributions of the SFP101 IC and of the whole

measurement circuit are minimal. Please see Fig. 7 for

the chart of typical current value error dependency on

the temperature.

NOTE5 Please see Fig. 8 for the chart of typical voltage

offset error dependency on the temperature.

NOTE6 In fact, parameter VX-ERR characterizes only the

performance of the voltage divider that scales the

external voltage to the nominal ±1 V input on the

SFP101 IC, and formed by two precision resistors

(R10 and R9); error contribution of the SFP101 IC is

minimal. Please see Fig. 9 for the chart of typical volt-

age value errors dependency on the temperature.

NOTE7 For all practical purposes, single-temperature cal-

ibration of the voltage value (at room temperature) re-

moves dependency of the measured voltage value from

the initial errors in the resistances of the two precision

resistors (R10 and R9) utilized in the external voltage

divider; the resulting specification VX-CAL-ERR basically

describes the errors in temperature tracking between

the resistances of R10 and R9, together with error

contribution from thermal drift for the built-in preci-

sion voltage reference of the SFP101 IC.

NOTE8 The SFP101 IC has a programmable value for the

parameter ISH-COUNT (and CSH-COUNT), via the setting

of register CUR_GAIN (address 0x43) that controls

the Full-scale voltage of the Programmable Gain Am-

plifier (PGA) for the current measurements. However,

with the particular shunt (and its resistance), utilized

on the module, the ISH-COUNT (and CSH-COUNT) are ini-

tialized to the single specific values shown in the Elec-

trical Specifications Table, and corresponding to the

Full-scale voltage of ±37.5 mV for the PGA. Likewise,

the specific setting of the PGA and thermal behavior

of the shunt defines the information presented for the

parameter ISH-PK.

Please see the description of CUR_GAIN register on

page 56 for more information.


Sendyne SFP101EVB

Measured Performance Data

Figure 6: Temperature Dependency of the Absolute Offset Error for Current Measurement

-0.01

-0.009

-0.008

-0.007

-0.006

-0.005

-0.004

-0.003

-0.002

-0.001

0

0.001

0.002

0.003

0.004

0.005

0.006

0.007

0.008

0.009

0.01

-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140

Cur

rent

Off

set E

rror

, A

Shunt Temperature, C°


Sendyne SFP101EVB

Figure 8: Temperature Dependency of Magnitude Error for Current Measurements, With Compensation

Figure 7: Temperature Dependency of Magnitude Error for Current Measurements, No Compensation


-1

-0.9

-0.8

-0.7

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140

Cur

rent

Mag

nitu

de E

rror

, %


-1

-0.9

-0.8

-0.7

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140

Cur

rent

Mag

nitu

de E

rror

, %


Sendyne SFP101EVB

Figure 9: Temperature Dependency of the Absolute Offset Error for the Voltage Measurements

Figure 10: Temperature Dependency of the Relative Magnitude Error for the Voltage Measurements

-0.1

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Sendyne SFP101EVB

Procedural Notes for Measured Performance Data

Current and Voltage Offset TestsData for the temperature dependency of the absolute

offsets for the current and voltage measurements are

obtained within a single test procedure.

Eight SFP101EVB modules are placed in a program-

mable thermal chamber, all shunts’ terminals are kept

open / not connected, individual voltage measurement

inputs on every module are shorted (i.e. individual

terminals Vx are shorted to their corresponding termi-

nals GND with a short wire clamped in connector J3).

The temperature of the thermal chamber is set to

-40 °C and allowed to stabilize before the data col-

lection starts. The actual data for the current, volt-

age, and temperature readings are acquired with the

sampling rate of 1 Hz, while the thermal chamber

is ramping at a rate of 0.3 °C per minute, over the

temperature range of -40 °C to +125 °C. Temperature

readings are for the on-board thermistor that is sens-

ing the temperature of the shunt in the middle. Test

duration for the data acquisition phase is slightly over

9 hours.

The time-domain data are transformed into the X/Y

charts with values of the current or voltage on the

Y/vertical axis, and measured thermistor temperature

on the X/horizontal axis.

The charts in Figures 6 and 9 show aggregate com-

bined testing data from 24 individual SFP101EVB

modules.

Current Magnitude Error TestEight SFP101EVB modules are placed in a program-

mable thermal chamber, all shunts are connected in

series with each other, and this string of shunts is

supplied with a precisely known DC current (approxi-

mately 20 A in magnitude).


-40 °C and allowed to stabilize before the data collec-

tion starts. The actual data for the current and tem-

perature readings is acquired with the sampling rate

of 1 Hz, while the thermal chamber is ramping at a

rate of 0.3 °C per minute, over the temperature range

of -40 °C to +125 °C. Temperature readings are for the

on-board thermistor that is sensing the temperature

of the shunt in the middle. Test duration for the data

acquisition phase is slightly over 9 hours.

Data for the current readings are divided by the value

of the precision DC current source, a quantity of 1 is

subtracted, and the result is multiplied by 100 in order

to produce the result expressed in percent.


chart with values of the relative current error on the



The charts in Figure 7 and Figure 8 show aggregate

combined testing data from 24 individual SFP101EVB

modules.

The data in Figure 7 is for SFP101EVB modules that

have been calibrated at a single, specifically random

temperature (to show the possible errors from cali-

bration at various temperatures). The data in Figure

8 is for the same SFP101EVB modules that have

been characterized throughout the whole operating

temperature range, and their individual Resistance

Temperature Dependence Tables (RTDTs) have been

uploaded to the module and utilized in the acquisition

of the data. As can be seen in Figure 8, with utilization

of the RTDTs, the errors due to changing temperature

are well below 0.05 %.


Sendyne SFP101EVB

Voltage Magnitude Error TestEight SFP101EVB modules are placed in a program-

mable thermal chamber, all shunts’ terminals are kept

open / not connected, individual voltage measurement

inputs on every module are interconnected in parallel

(i.e. all individual terminals Vx are shorted together to

a wire supplying the test voltage, and all correspond-

ing GND terminals are shorted together to a wire

providing a return for the test voltage). The precisely

known test voltage is set to approximately 25 Vdc in

magnitude.


-40 °C and allowed to stabilize before the data collec-

tion starts. The actual data for the voltage and tem-

perature readings are acquired with the sampling rate

of 1 Hz, while the thermal chamber is ramping at a

rate of 0.3 °C per minute, over the temperature range

of -40 °C to +125 °C. Temperature readings are for the

on-board thermistor that is sensing the temperature

of the shunt in the middle. Test duration for the data

acquisition phase is slightly over 9 hours.

Data for the voltage readings are divided by the value

of the precision DC voltage source, a quantity of 1 is

subtracted, and the result is multiplied by 100 in order

to produce the result expressed in percent.


chart with values of the relative voltage error on the



The chart in Figure 10 shows aggregate combined test-

ing data from 24 individual SFP101EVB modules.


Sendyne SFP101EVB

Absolute Maximum Ratings

Parameter RatingTA Ambient Operating and

Storage Temperature,

SFP101EVB Assembly

-40 °C to +125 °C

TIOCBL Operating and Storage

Temperature, Serial-to-USB

interface cable

-40 °C to +85 °C

VCC Supply Voltage 4.5 V to 5.5 V

VJ2.4-MAX Serial Receive Input,

Maximum Voltage Range

-0.5 V to VCC + 0.5 V

ISH-TRANS Shunt Transient

Over-Current, 5 s maximum

duration

±3 kA

VMAX-OVLD-TRANS Short Time

Maximum Input Voltage Over-

load, External Voltage Input, 5s

maximum duration

±300 V

ESD (Human Body Model) ±2 kV

Stresses above those listed under Absolute Maximum

Ratings may cause permanent damage to the device.

This is a stress rating only; functional operation of the

device at these or any other conditions above those

indicated in the operational section of this specifica-

tion is not implied. Exposure to absolute maximum

rating conditions for extended periods may affect

device reliability.

ESD CAUTION

ESD (electrostatic discharge) sensitive device.

Electrostatic charges readily accumulate on the

human body as well as test equipment, and can

discharge without detection. Although this product

features protection circuitry, damage may occur in

devices subjected to high energy ESD. Proper ESD

precautions should be taken to avoid performance

degradation or loss of functionality.


Sendyne SFP101EVB

Functionality Overview

The SFP101EVB is capable of simultaneously mea-

suring current, voltage, and temperature; in addition

three independent temperature points are measured

on the shunt.

Data are provided in response to the Host requests;

please see the full description and examples in the

Communications section of this document.

Individual data acquisition modalities are described

below.

Current Measurements with the SFP101 The SFP101 measures current by measuring voltage

across a resistive shunt, according to Ohm’s Law.

The SFP101 IC is specifically designed to operate with

shunts that have extremely low resistance (and there-

fore – low heat loss / power dissipation).

The SFP101 implements several of Sendyne’s patented

and patent pending technologies in order to achieve

precision in field current measurements comparable

to the precision of metrology grade lab instruments.

Resistive Current ShuntSeveral sources affect the accuracy of current mea-

surements; however, in a properly designed system

the most significant contributor to errors is the

resistive shunt itself. The factors influencing the ac-

curacy include: stability of the shunt’s resistance with

temperature and time; presence of thermoelectrically

induced error voltages; and mechanical size (i.e. its

ability to dissipate heat generated by I2R Joule heat-

ing, that in turn elevates the temperature of the shunt

and causes changes in resistance to the shunt).

The resistive portion of shunts used for current

measurements is specifically constructed from unique

alloy materials that have a very small Temperature

Coefficient of Resistance (TCR). Excluding the second-

ary effects, the resistance of the shunt is determined

by the following equation:

R = R0[1 + α(T – T0)] [1]

where R0 is the known resistance (in Ohms) at known

temperature T0 (in degrees K), α is the Temperature

Coefficient of Resistance (with the units of 1/K),

GREF

G

G

×1

CURRENTSENSING

½ AVDD

ADC1

11

15

14

20

19

7

8

Calibration Controls

1k

RF

RF

SW SW

AGND

CRF

CRF CF

RF

RF

SW SW

AGND

CRF

CRF CF

CB

AGND

SHUNT+

SHUNT-

VREF

24 VH

23

AGND

AVDD Figure 11: Current Measurement Interface


Sendyne SFP101EVB

R is the unknown value of resistance at an arbitrary

temperature T, and the difference (T – T0) is relatively

small (so that α can be assumed constant).

Devices that operate based on the relationship de-

scribed in Equation 1 are used for precision tempera-

ture measurements; the so-called Resistance Tem-

perature Detectors (RTD), and specifically platinum

RTD (PRTD) are widely used in science and industry,

due to relatively large, stable, and predictable Tem-

perature Coefficient of Resistance. For a reference, the

TCR of platinum and of copper (a common material

used in electronics) is about 4∙10-3 K-1.

However, in general, the temperature coefficient of

resistance α is itself dependent on temperature, and

especially so for the alloys used in the construction of

precision shunts.

For shunts, the objective is to make the Temperature

Coefficient of Resistance as small as possible, with the

intent of having constant resistance during tempera-

ture changes.

It should be appreciated that the Temperature Coef-

ficient of Resistance for materials developed for

resistive shunts is less than 10-4 K-1, at the extremes of

a relatively large temperature range, and approaches

zero at room temperature (~23 °C), where the sign of

the temperature coefficient may also change.

A chart of the effects of temperature dependency of

SFP101EVB shunt’s resistance can be seen in Fig. 7 in

the Measured Performance Data section.

Other major contributors of the current measurement

errors in the shunt are the small voltages produced by

thermoelectric effects due to thermal gradients in the

shunt and in the sensing connections (leads or wires).

The magnitude of these error voltages is typically less

than several hundred microvolts, and manifest them-

selves when the current passing through the shunt

produces heat, or the ambient temperature changes.

The shunt’s external connections (that are necessarily

made with heavy-gauge wires for low resistance) may

also conduct heat from nearby sources and introduce

temperature gradients.

Ordinarily, thermoelectric voltages in the shunt would

not greatly upset the measurements, as the apparatus

used to measure the voltage drop in a shunt would

have an offset error voltage on the order of millivolts.

However, for the SFP101 that is operating with sub

100 nV maximum offset voltage over wide operat-

ing temperatures, the thermoelectric voltages are the

primary source of errors.

That is why the sensing connections from the resis-

tive shunt to the measurement circuit are created in a

particular, Sendyne-specific, patent pending method.

The sensing leads are made from the same material

as the shunt’s active resistive part, and the leads are

attached using laser micro welding. This arrangement

generates thermoelectric voltages that are at least an

order of magnitude smaller than using conventional

well-designed construction.

It should be noted that specifications for current offset

errors, both in this document and in the SFP101

datasheet, are based on measurements made with

the SFP101 attached to a shunt; an IC by itself would

produce an offset value that is immeasurably small.

Dual-channel 24-bit ΣΔ ADCFig. 11 illustrates the basic current measurement

circuit and interface of the SFP101. The SFP101

measures current by measuring the voltage across a

resistive shunt. The Current Measurement Section of

the SFP101 consists of two identical and matched am-

plification channels with high-impedance differential

inputs, both providing data to a 24-bit ΣΔ ADC (Ana-

log to Digital Converter). The two ADC channels are

used alternatively for data acquisition and continuous

calibration.


Sendyne SFP101EVB

Reduction of ErrorsThe data acquisition circuit of the SFP101 provides

two distinct mechanisms for reduction of errors in

current readings. The first mechanism utilizes low-

pass filtering and long integration times, dynamically

adjustable to the signal acquisition frequency, for

minimization of the bandwidth and noise averaging.

This technique is field proven and used in metrology

instruments, such as high precision nanovoltmeters.

It is quite effective for attenuation of thermal noise

(Johnson noise) present in the shunt’s measurements.

The second error reduction mechanism the SFP101

implements accounts for the thermoelectric EMF

offsets developed along the whole signal path from the

shunt to the ADC inputs inside the IC.

Continuous CalibrationFor any measurement IC, external connections to a

shunt include dissimilar materials at different tem-

peratures. This results in a number of thermoelectric

EMF sources that add algebraically to the measured

signal value. This has traditionally been the main ob-

stacle for achieving a wide dynamic range of measure-

ments using shunts. These errors are normally in the

range of tens of microvolts up to tens of millivolts, and

are highly dependent on the physical implementation

of the circuit.

Sendyne addresses this issue utilizing its patented and

patent pending technology that allows calibration for

all thermoelectric errors that originate at the sensing

leads of the shunt, including all filter components,

their connections, as well as the connections of the IC

leads themselves (including bonding connections in-

side the IC package). A complete measurement circuit

around the SFP101 (from shunt to digital interface)

attains long-term drift / offset error that is typically

better than 100 nanovolts over the whole operating

temperature range.

Anti-aliasing and RFI/EMI FilterThe SFP101 allows interfacing to RFI/EMI/anti-alias-

ing filters without any degradation of the measure-

ment accuracy. Fig. 10 shows the suggested interface

between the resistive shunt and the SFP101.

Identical filters (but not necessarily perfectly

matched) are present at both current measurement

inputs of the IC. A set of analog switches controls the

signal path between the shunt and the IC input pins.

These filters are necessary to remove interference

from possibly large RF fields ever present near power

circuits, and from nearby RF emitters such as WiFi

and cellular communication devices. The filters’ time

constants are chosen such that they also serve an anti-

aliasing function for the A/D.

Components used in these filters are not of a precision

variety, and do not need to match each other between

the two channels. However, the filters’ components

should be precise enough to satisfy RF filtering and

anti-aliasing functionality. Typically, inexpensive 5 %

tolerance components are sufficient for this purpose.

Presence of the filters at the inputs of the amplifica-

tion channels allows for very high performance in

respect to rejection of EMI/RFI (Electromagnetic/

Radio Frequency Interference).

In order to achieve the best noise and linearity per-

formance, the two current amplification and sens-

ing channels of the SFP101 are operated with input

(common-mode) voltage near the middle of the analog

IC supply range. The SFP101 IC generates this voltage

at pin 11.

Uncompensated JointsThere are six non-compensated solder joints connect-

ing the leads of the MOSFET switches and sensing

leads of the shunt. These are arranged in a PCB layout

that effectively creates an isothermal block (an area


Sendyne SFP101EVB

with uniform and constant temperature) for all of

these joints, and assures that thermoelectric errors

from these six solder joints are null due to uniform

temperature. This arrangement has been experimen-

tally verified at different temperatures by various tests

utilizing thermal chamber and precision thermometry.

“High” and “Low” Side MeasurementsOne of the unique features of the SFP101, when

utilized in the recommended circuit configuration,

is the ability to perform both “high” and “low” side

current measurements. This is due to the fact that,

with galvanic isolation for both power and communi-

cations, it does not matter if the current is sensed at

the “low” (ground) or “high” (power supply) side, or

anywhere in-between. Of course, the user should be

aware of the polarity (sign) of the sensed current, as

depending on the exact connection scheme, it may be

different between the “high” or “low” sensing method.

There is an advantage in having specific configurations

when both current and voltage sensing are utilized;

more information on this is provided in the Voltage

Measurement Section.

Analog SwitchesSimple MOSFET transistors are used as analog

switches to perform automatic measurement sys-

tem calibration. Because the maximum voltage to be

disconnected is less than 100 mV (e.g. 1 kA current

going through 100 μΩ shunt will create only a 100 mV

voltage drop), it is possible to use a single MOSFET

transistor as a bidirectional-blocking analog switch.

The parasitic diode present in every MOSFET struc-

ture will never turn on due to the low voltage across

the switch when it is open.

Devices used for these switches are monolithic dual-

MOSFET parts. The supply voltage for the MOSFET-

driver buffers is an unregulated voltage ISOFHV that

is provided from an isolating DC/DC converter. A

low-power voltage regulator uses the same voltage to

generate accurate supply levels for AVDD and DVDD.

Again, as stated above, the measurement data from

the IC are continuous, and internal re-calibration does

not produce any interruptions or data dropouts. The

actions of the calibration are automatic and transpar-

ent to the user; no intervention or management is

required.

Coulomb CountingThe measured values of the current are automati-

cally accumulated in the coulomb count registers. The

SFP101 offers three independent (but closely-coupled)

coulomb count registers -- one for the value of the

total integrated charge, and one each specifically for

charge and discharge currents. The sum of the values

in the CHARGE_ACC and DIS_ACC is always equal to

the value in the CUR_ACC.

Coulomb counting operations are controlled by a state

machine based on the present value of the current and

two programmable threshold parameters, C_TRESH

and D_TRESH, the charge threshold and discharge

threshold.

If the value of the present current sample is higher

than the C_TRESH, then the accumulation of the

charge will be redirected to the register CHARGE_

ACC; if the present current sample is lower than the

D_TRESH, then the accumulation of the charge will

be redirected to the register DIS_ACC; if neither of

these conditions is met, accumulation of the charge

will be directed to the same register as for the previous

sample.

This logic-driven coulomb counting operation allows

for drastic reduction of the accumulated errors in the

coulomb counting registers (due to averaging out of

the noise, instead of the rectification and integration

of noise in both Charge and Discharge accumulators).

The difference between the values of the C_TRESH

and D_TRESH parameters should be higher than the


Sendyne SFP101EVB

maximum peak-to-peak noise in the current measure-

ments; in practice, the C_TRESH should be initialized

to a small positive value, and D_TRESH to a small

negative value or zero.

It should be noted that the accuracy of the accumu-

lated charge quantity in the coulomb count registers is

higher than would be possible by reading and accumu-

lating individual current measurements, due to a pre-

cisely uniform sampling rate and absence of jitter, and

especially so if automatic temperature compensation

is employed for the resistance changes of the shunt.

If full-scale (positive or negative) current measure-

ments are accumulated continuously, the coulomb

count register is capable of collecting up to 43 years

of data without over- or under-flow. The host control-

ler is advised when accumulated charge is over half of

the maximum amount (e.g. a flag is set and reported

when the absolute value of the accumulated data ex-

ceeds ½ of the total maximum value); if the coulomb

count register is started from zero value, it would take

over 21 years for the ½ range flag to be set; the host

controller therefore has another 21 years to deal with

the situation by possibly resetting the coulomb count

register back to zero.

Shunt CalibrationBoth initial tolerance of the shunt, and variability in-

troduced by leads’ attachment, means that any shunt

will have a different resistance value than other shunts

from the same manufacturer created in the same lot.

In order to produce very accurate current (and related

charge accumulation) measurements, the SFP101EVB

module is calibrated at room temperature. Precisely

known current is passed through the shunt, the data

from SFP101EVB is accumulated and averaged (to re-

duce the influence of noise), and the calibration value

is calculated.

The SFP101 provides 16-bit non-volatile storage reg-

ister for shunt calibration data, register SHNT_CAL

(address 0x41). The data in SHNT_CAL represents a

value between -0.5 and +0.5, it is able to accommo-

date shunts with resistance variations (referenced to

the nominal value) from -33 % to +100 %.

The user can calculate the effect of the calibration ac-

cording to the following formula:

ICALIBRATED = IRAW × (216 + SHNT_CAL) / 216

where IRAW and ICALIBRATED are correspondingly the

raw and calibrated result for the measurement of

current (that depends on the resistance value of the

shunt), and considering that SHNT_CAL is a signed

2’s complement 16-bit value. It should be clear, when

SHNT_CAL = 0, then ICALIBRATED = IRAW.

For other values of calibration data, it is possible

to compensate for the shunt’s resistance deviations

as large as –33 % to +100 %; the granularity of the

adjustment is 0.00153 % when the SHNT_CAL is near

zero, and respectively 0.0008 % to 0.003 % at the max-

imum and the minimum values of the SHNT_CAL; for

all practical reasons, the granularity of the adjustment

is at least over an order of magnitude better than the

expected accuracy of the measurements.

If not disabled by the SHNT_CAL_DIS control flag

in register COMP_CTRL (address 0x44, bit 0), the

SFP101 automatically applies the calibration data

and calculates the calibrated current value according

to the formula above; this is especially convenient in

respect to the accumulated charge data in the built-in

coulomb counting registers.

The non-volatile register SHNT_CAL is not intended

for periodic updates while the IC is performing normal

operations (i.e. making measurements and acquiring

data); it should only be initialized during testing or

calibration operations; the IC should then be reset or


Sendyne SFP101EVB

the power should be cycled, in order to start normal

operations.

Please contact Sendyne for information on performing

the calibrations and for derivation of the SHNT_CAL

value.

Shunt Thermal CompensationThe SFP101 has a built-in mechanism for automatic

compensation of the resistance changes of the shunt

with changes in temperature.

To perform this automatic compensation, the IC

utilizes the readings from the on-board thermistor 2

as measurement of the temperature of the shunt (the

Y value reported in register TEMP2Y_OB_OUT, ad-

dress 0x93). The calculated Y value for the on-board

thermistor 2 is internally converted to temperature

(in degrees Celsius, and using the look-up table as

described in the Temperature Measurements section).

The temperature of the on-board thermistor 2 is in

turn converted to a gain adjustment factor, and ap-

plied as shown below.

This functionality is implemented with the aid of a

look-up table, a so-called Resistance Temperature De-

pendence Table (RTDT). The RTDT has 256 entries,

each entry having 32-bit data; thus the total size of the

table is 1 kB.

This table has a unique compensation value for dis-

crete temperatures spaced 1 °C apart. Compensation

values for the shunt’s temperatures that fall between

the discrete entries in the table are calculated by

a proprietary Sendyne algorithm using linear ap-

proximation and 2nd-order correction values that are

incorporated into every table entry.

The look-up fidelity of the compensation table is very

high. The maximum calculation errors due to both the

approximation and 2nd-order correction are less than

±1 ppm. As a result, calculation errors have a negli-

gible effect on the accuracy of the reported current

measurements.

Compensation of the current measurement data is

done according to the following formula:

ICOMP = ICALIBRATED ×

(Compensation_Table_Value) / 223

where ICOMP and ICALIBRATED are correspondingly the

compensated and calibrated (see the section on cali-

bration above) results for the measurement of current,

and considering that Compensation_Table_Value

is an unsigned 24-bit value, representing compensa-

tion gain from 0 to 2. When Compensation_Table_

Value=0x800000 (representing compensation

gain = 1), then ICOMP = ICALIBRATED.

If not disabled by the SHNT_COMP_DIS control flag

in register COMP_CTRL (address 0x44, bit 4), the

SFP101 automatically applies the compensation data

and calculates the compensated current value accord-

ing to the formula above; this is especially important

in respect to the accumulated charge data for the

built-in coulomb counting registers.

Practical benefit of the thermal compensation will

depend on the method of generation for the thermal

dependency data. If a common (single) RTDT table

is made for the whole production lot of shunts, using

testing of a limited number of representative samples

of that production lot, it could be expected that with

thermal compensation the maximum magnitude error

for the entire operating temperature range of -40 °C

to +125 °C will be less than ±0.05 %. For shunts that

have been individually characterized, an error of less

than ±0.005 % (±50 ppm) is readily achievable.

If thermal compensation is employed, the IC must

have a Celsius look-up table for the “on-board” therm-

istors, as well as the RTDT table.


Sendyne SFP101EVB

More details are provided later in this document in the

section describing FLASH tables.

Please contact Sendyne for information on producing

the data for thermal compensation of the shunt and

for generation of the RTDT compensation table.

Current Measurement ReportingThe SFP101 reports the measured values for the cur-

rent measurements as the averaged value for the time

interval between the previous measurement read-out

and the present data read-out. Measurement noise is

reduced and effective resolution is improved (being

able to resolve smaller current changes) if the read-out

frequency is reduced, allowing for a longer averaging

time.

The measured current value is reported in response to

a request by a Host controller (or a PC that is execut-

ing Sendyne’s control software application).

Specifically, the current value data is located in reg-

isters called CUR_OUT: Current Measurement Data

Output Registers; the data is 24-bit 2’s complement

signed number. One count of the least-significant bit

of this number represents the current that is specified

as ISH-COUNT; it is typically 61.19 µA.

Therefore the actual current measurement value can

be calculated as:

IRAW = ISH-COUNT × CUR_OUT [2]

where IRAW is the raw (uncalibrated) current mea-

surement value, and other parameters are described

above. Notice that if the value 61.19 µA is directly

utilized for calculations (without scaling or convert-

ing into different units), the resulting product IRAW

describes the current in units of microamperes.

In order to apply the calibration value, the raw current

value is multiplied by an adjustment coefficient calcu-

lated from the calibration value:

ICALIBRATED = IRAW × (216 + SHNT_CAL) / 216

= ISH-COUNT × CUR_OUT

× (216 + SHNT_CAL) / 216 [3]

where ICALIBRATED is the current measurement ad-

justed for calibration, and SHNT_CAL is the 16-bit 2’s

complement calibration data stored in the nonvolatile

memory of the SFP101 IC and representing a value

between -0.5 and +0.5.

Essentially, the expression [(216 + SHNT_CAL) / 216]

is a linear gain adjustment coefficient; it is always

positive and can vary anywhere from 0.50 to 1.50.

Note that if SHNT_CAL = 0, then ICALIBRATED = IRAW.

Please note that if the current calibration is employed,

it is not required to utilize a precise value of the

ISH-COUNT parameter for calculations (61.19 µA), it

would suffice to have any value that is near the nomi-

nal, but still well within the adjustment range

(–33 % to +100 %) of the calibration process; this

could be used to simplify computations if integer cal-

culations are employed on a low-performance

microcontroller in the Host.

Of course, exactly the same value of ISH-COUNT must be

utilized for both calculations of SHNT_CAL data and

ICALIBRATED value.

In fact, the value of 62.5 µA (1/16000 A) is used for

the ISH-COUNT parameter in SFP101EVB calibrations

and SFP101SFT software application.

The same linear gain adjustment coefficient [(216 +

SHNT_CAL) / 216] is also applicable to the value of the

accumulated charge in the coulomb counting regis-

ters; see the next section.

If the SFP101 is applying the calibration adjust-

ment automatically (i.e. it is not prohibited by the

SHNT_CAL_DIS control flag), then the equation for


Sendyne SFP101EVB

calibrated current value is simplified to:

ICALIBRATED = ISH-COUNT × CUR_OUT [3a]

Coulomb Counting ReportingAt the request of the Host, the SFP101 simply reports

the present value of the coulomb counting accumula-

tors; the data is situated in the registers CUR_ACC,

CHARGE_ACC, and DIS_ACC that store 64-bit 2’s

complement (signed) values. The following discus-

sion is equally applicable to any of the three coulomb

counting registers.

The actual accumulated charge (coulomb count) value

can be calculated as follows:

CCALIBRATED = ISH-COUNT × (CUR_ACC / 800)

× (216 + SHNT_CAL) / 216 [4]

where CCALIBRATED is the accumulated charge value

adjusted for calibration, ISH-COUNT is the resolution of

current measurements, and SHNT_CAL is the 16-bit

2’s complement calibration data stored in the non-

volatile memory of the SFP101 IC and representing a

value between -0.5 and +0.5.

If the SFP101 is applying the shunt calibration adjust-

ment automatically (i.e. it is not prohibited by the

SHNT_CAL_DIS control flag), then the equation for

calibrated value is simplified to:

CCALIBRATED = ISH-COUNT × (CUR_ACC / 800) [4a]

Note that the factor 1/800 represents the effective

time between the current data samples (with two

independent channels utilized in the current measure-

ments, each having 400 Hz sampling rate); it is simply

the time value in the calculations of charge:

ΔCharge = Current × ΔTime [5]

where current value is assumed to be constant

throughout the duration of ΔTime.

The reader is reminded that parameter ISH-COUNT

should have exactly the same value as used for current

calibration.

If precise value of the accumulated charge is not

required, it could be calculated using a simplified

equation:

CCALIBRATED = CSH-COUNT × CUR_ACC [6]

where CSH-COUNT is the accumulated charge measure-

ment resolution value from the electrical specifica-

tions table (typically 76.49 nC).


Sendyne SFP101EVB

Voltage Measurements with the SFP101 A dedicated 24-bit ΣΔ ADC is utilized for voltage

measurements (as well as for temperature-related

measurements). The Sendyne SFP101 will interface

to a simple resistive voltage divider that can scale the

desired voltage measurement range to the nominal

input of ±1.000 V. Accuracy and thermal drifts of the

voltage measurements are determined by the accuracy

of this voltage divider. Furthermore, calibration of

the voltage measurement channel of the IC installed

in a particular circuit is possible; the SFP101 stores

the calibration constant internally in the non-volatile

memory. If not disabled by the VOLT_CAL_DIS con-

trol flag, the SFP101 applies this voltage calibration

data and calculates the corrected measurement values

automatically.

An example of the performance possible with a single

(room) temperature calibration is reported in electri-

cal specifications table (VX-CAL-ERR), and dependency

of the errors on temperature is demonstrated in the

charts of Fig. 9 and Fig. 10.

Fig. 11 illustrates a typical interface for acquiring volt-

age measurements. The reference point VX-REF (0 V) of

the voltage measurement is the same as the negative

terminal of the current measurement shunt, and the

measured voltage value can be positive or negative.

The application circuit can tolerate momentary over-

voltage conditions to ±300 V, and is highly protected

from ESD. The actual rating depends only on the

capabilities of the components used in the divider.

With the divider values shown, the nominal continu-

ous full-scale input voltage is ±150 V. Over-range

readings up-to ±241 V are accommodated without loss

of accuracy.

The value of the continuous maximum full-scale work-

ing voltage is primarily determined by the specifica-

tions of the upper divider resistor (R10), a 1206 SMT

component with Maximum Working Voltage speci-

fication of 150 V. The maximum continuous voltage

rating is first and foremost established by the physical

size of this component. If higher continuous full-scale

voltage is required, an industry-accepted practice of

connecting multiple resistors in series (so as to spread

the total voltage across several components) should

be utilized; a string of series-connected resistors can

be attached externally to the SFP101EVB module. The

user is cautioned to pay specific attention to possible

reduction of accuracy due to tolerances of multiple

series-connected resistors and their thermal tracking

between each other and to the lower resistor (R9) of

the voltage divider.

The voltage sensing circuitry in SFP101 has true

differential inputs; however, for the largest full-scale

measurement range the negative input of the differen-

tial sensing pair is connected to the mid-point of the

analog supply voltage, as shown in Fig. 11 utilizing the

same internal bias generator as the current measure-

ment channels. In this way, both positive and nega-

tive voltages can be measured, with equal full-scale

excursions.

As mentioned previously, the SFP101EVB circuit is

able to perform both “high” and “low” side current

measurements. In order to exclude shunt voltage

drop as well as errors associated with cables, it may

be advantageous to have the SFP101EVB connected

in a specific way depending on the configuration of

the current sensing scheme. Illustrated in Fig. 13 are

two configurations that are suitable for simultaneous

measurements of current and voltage on a multi-cell

battery. The common element in both configurations

is the connection of the negative side of the shunt

(that is also a negative reference point for the volt-

age measurements) to the battery, irrespective of the

“high” or “low” side metering for the current.


Sendyne SFP101EVB

In the case of “low” side sensing (presented on the

left side of Fig. 13), the measured current will read

positive when the battery discharges; the measured

voltage will also be positive.

In the case of “high” side sensing (illustrated on the

right side of Fig. 13), the measured current will read

negative when the battery discharges; the measured

voltage will also be negative.

In either case, the voltage drop across the shunt will

not impede the voltage measurement. It is strongly

recommended to analyze the whole current charge /

discharge path in order to organize the cabling to have

the minimum impedance between the battery and the

negative terminal of the shunt, for the purpose of hav-

ing correct measurements of the voltage.

Similar considerations apply when the desired

measurement node is, for example, a charger or a

specific load that should be monitored. In this case

it is preferred that the negative terminal of the shunt

is connected directly, or as close as possible, to the

device being monitored.

Voltage Measurements’ CalibrationThe SFP101 provides a 16-bit non-volatile storage

register for calibration data of the voltage measure-

ment channel, register VOLT_CAL (address 0x55).

The data in VOLT_CAL represents a value between

-0.5 and +0.5, and it is able to accommodate input

voltage divider ratio variations (referenced to the

nominal value) of ±50 %.

The user can calculate the effect of the calibration ac-

cording to the following formula:

VCALIBRATED = VRAW × (216 + VOLT_CAL) / 216

where VRAW and VCALIBRATED are correspondingly

the raw and calibrated result for the measurement of

voltage (that depends on the divide ratio of the input

divider), and considering that VOLT_CAL is a signed

2’s complement 16-bit value. When VOLT_CAL = 0,

then VCALIBRATED = VRAW.

If not disabled by the VOLT_CAL_DIS control flag

in register VOLT_GCCH (address 0x58, bit 0), the

SFP101 automatically applies the calibration data and

GREF

x1

x1

VOLTAGESENSING

½ AVDD

ADC2 25

26

11

4.99k

1.00M

VX

1k

VX-REF

CB

AGND

SHUNT+

SHUNT-VREF

24

AVDD

23

AGND

Figure 12: Voltage Measurement Interface


Sendyne SFP101EVB

calculates the calibrated voltage value according to the

formula above; essentially, the calibration removes the

errors of the input voltage divider at one specific tem-

perature (i.e. the temperature of the voltage divider at

a time of calibration); accuracy of the voltage mea-

surements for any other temperatures of the voltage

divider will mostly depend on the thermal tracking

between the elements of the voltage divider.

The non-volatile register VOLT_CAL is not intended

for periodic updates while the IC is performing normal

operations (i.e. making measurements and acquiring

data); it should only be initialized during testing or

calibration operations; the IC should then be reset or

the power should be cycled, in order to start normal

operations.

Please contact Sendyne for information on performing

the calibrations and for derivation of the VOLT_CAL

value.

Voltage Measurement ReportingThe SFP101 reports the measured values for the volt-

age measurements as the averaged value for the time

interval between the previous measurement read-out

and the present data read-out; measurement noise is

reduced and effective resolution is improved (being

able to resolve smaller current changes) if the read-out

frequency is reduced, allowing for a longer averaging

time.

The measured voltage value is reported in response to

a request by a Host controller (or a PC that is execut-

ing Sendyne’s control application).

If an instantaneous voltage reading is required after a

long period of inactivity (i.e. the Host was not asking

for voltage data for a long time interval), a double-

read technique should be used: the first reading will

provide an averaged value from the time the unit was

last asked for data; immediately following this the

second reading will provide the instantaneous value.

Specifically, the voltage value data is located in regis-

ters called VOLT_OUT: Voltage Measurement Data

Output Registers; the data is 24-bit 2’s complement

signed number. One count of the least-significant bit

of this number represents the voltage that is specified

as VX-COUNT; it is typically 28.8 µV.

SYSTEM COMMON/GND

SFP101 MODULE

VX

SHUNT+

SHUNT-

BATT

ERY

LOAD ORCHARGER

SYSTEM COMMON/GND

VX

ONLY one of the shown GND connections can be used; however,

both are permitted

ISOLATED I/OTO/FROMHOSTCONTROLLER

LOAD ORCHARGER

BATT

ERY

SHUNT+

SHUNT-

ISOLATED I/OTO/FROMHOSTCONTROLLER

SFP101 MODULE

Figure 13: Voltage Measurement with Low-side or High-side Current Sensing


Sendyne SFP101EVB

Therefore the actual voltage measurement value can

be calculated as:

VX-RAW = VX-COUNT × VOLT_OUT [7]

where VX-RAW is the raw (uncalibrated) voltage mea-

surement value, and other parameters are described

above. Notice that if the value 28.8 µV is directly

utilized for calculations (without scaling or convert-

ing into different units), the resulting product VX-RAW

describes the voltage that has the units of microvolts.

If calibration of the voltage measurements is required,

a procedure similar to the one outlined for the current

measurements should be utilized.

If not disabled by the VOLT_CAL_DIS control flag,

the SFP101 automatically applies the voltage calibra-

tion data, and the formula for the read-out of the volt-

age measurements becomes:

VCALIBRATED = VX-COUNT × VOLT_OUT [7a]


Sendyne SFP101EVB

Temperature Measurements with the SFP101 The Temperature Measurement Section is depicted

in Fig. 14. Two differing circuits are employed for the

“remote” and “on-board” temperature sensing.

Both “remote” and “on-board” temperature measure-

ments utilize NTC (negative temperature coefficient)

thermistors, with 10 kΩ nominal resistance (at 25 °C)

and 1 % tolerance. These sensors with 1 % tolerance

permit better than ±1 °C measurement accuracy over

the full operating temperature range

of –40 °C to +125 °C.

The temperature measurement accuracy is not limited

by the capabilities of the SFP101 IC; it is fully deter-

mined by the accuracy and performance of the sensors

and reference resistors engaged in the circuit.

The selected nominal value of 10 kΩ is a compromise

between the circuits’ susceptibility to noise, low-power

operations, and accuracy. The users may employ

thermistors with differing nominal resistances and

tolerances; performance of the circuit will vary accord-

ingly, and circuits’ components around the thermistor

may need to be adjusted.

Operations with thermistors that have room-tempera-

ture resistance at or below 1 kΩ are not recommended

due to relatively high current consumption.

Thermistors used as temperature sensors are typically

characterized by low-cost (for a given level of accura-

cy, as opposed to other types of temperature sensors)

and wide operating temperature range comparable to

the operating range of performance electronic circuits

and batteries; however, the response of the thermistor

is highly non-linear over the full operating tempera-

ture range.

At low temperatures, the changes of the thermistor’s

resistance are large, while at high temperatures, the

changes in conductance (1/R) are high. That is why

the thermistor conditioning circuits often include lin-

earization components in the form of precision (and

temperature-stable) resistors.

Linearization can be implemented with a “series” or

a “parallel” linearization resistor; the impedance of

the circuit and current consumption in the “series”

approach changes dramatically with the temperature

(becoming more susceptible to noise at lower tem-

peratures).

On the other hand, Sendyne uses “parallel” lineariza-

tion that is characterized by low impedance at high

temperatures and impedance that is not larger than

room-temperature resistance of the thermistor at low

temperatures. This circuit is advantageous from the

robustness to noise point of view.

A typical chart of linearized (and intrinsic non-lin-

earized) thermistor’s resistance is shown in Fig. 15.

The linearization resistor is connected in parallel to

thermistor; the value of this resistor is equal to 10 kΩ,

the same as the room-temperature (defined as 25 °C

for thermistors) resistance of the thermistor.

Notice that at the 25 °C point, the value of the linear-

ized resistance is exactly ½ of the nominal value of

thermistor, or 5 kΩ.

The SFP101 reports the thermistors’ resistance values

via an internally calculated intermediate parameter Y,

defined as the ratio between the resistance of the

thermistor in parallel with reference (and lineariza-

tion) resistor, and resistance of the reference resistor,

as shown in Equation 8:

[8]

Utilization of Y parameter allows for freedom in

selecting thermistors and reference resistors, without

||TH REF

REF

R RYR

=


Sendyne SFP101EVB

locking the user to any one particular part or value.

Moreover, parameter Y has other beneficial proper-

ties; in particular it has a naturally bounded value

between 0 and 1 and its value does not depend on

reference voltage (for the A/D) or the level of excita-

tion voltage for the thermistor circuits.

Users are free to apply their favorite temperature

calculation method from the thermistor’s resistance;

an example utilizing the Steinhart-Hart equation is

provided later in this document.

In general, to calculate the temperature, it is required

to know the reference resistor value, as well as charac-

teristics of the thermistor.

For the utilization of Steinhart-Hart equation it is nec-

essary to know a set of three (3) values that are called

Steinhart-Hart coefficients.

While both “remote” and “local” sensing circuit

employ “parallel” linearization, their operations are

different.

The “remote” temperature measurement circuit is cin-

gulated in Fig. 16. It is optimized for operations with

a twisted-pair cable between the sensor (thermistor)

and the SFP101.

As can be seen in Fig. 16, there are high-valued resis-

tors between the connections of the thermistor and

the pins of the IC; this promotes high resistance to

ESD events.

×1

×1

×1

TEMPERATURE SENSING

SW

AGND

ADC2

4.99k

1k

1k t

10k

42

41

40

39

AVDD

10.0k

5k

10k

AVDD

AGND

SW

10.0k

13

12

18

27

28

t

SW SW SW

t t

Thermistor

Selection

Controls

REMOTETHERMISTOR

LOCALTHERMISTORS

VREF

24

AVDD

23

AGND

Figure 14: Temperature Measurement Interface


Sendyne SFP101EVB

Acquisition of the data from a “remote” thermistor

is performed by two separate voltage measurements;

one measuring the voltage drop across the parallel

combination of the “remote” thermistor and a 10.0 k

reference/linearization resistor, between pins 28 and

27, and the other measuring the voltage drop on the

4.99 k reference resistor (that is also of the precision

variety), between pins 12 and 28.

Since the current causing both voltage drops is the

same, the resistance ratio between the two mea-

sured parts of the circuit is equal to the voltage ratio

between the two measurements; in other words, the

desired value of the parameter Y is the ratio between

V10.0 k over 2 × V4.99 k. The value of the 4.99 k resistor

is intentionally selected to be as close as possible to ½

of the resistance of the 10.0 k reference/linearization

resistor; this simplifies the calculations (and is respon-

sible for exactly ×2 in the denominator).

The other reason for selecting the bottom resistor’s

value to be one-half of the reference/linearization

resistor (rather than the same resistance) is to better

match the permitted input range of the pins on

SFP101 IC to the actual voltage excursions developing

in the “remote” thermistor sensing circuit over the full

operating temperature range.

The switch connecting the bottom resistor to AGND

can be made to open, in order to stop the current

consumption in this sensing circuit; it may be use-

ful if “remote” temperature measurements are very

infrequent, and prolonged periods of time may pass

between individual measurements.

While measurements of the “remote” thermistor are

made, the switches in the “local” thermistors’ mea-

surement circuit are open, and this part of the circuit

does not consume any excitation current.

The “on-board” temperature measurement circuit is

shown in Fig. 17. It is optimized for operations with

multiple sensors connected to a single differential

sensing input on the SFP101. This section of the

circuit is primarily intended for temperature sensing

at three (3) independent points on the current shunt.

Since this circuit is optimized for multiple sensors

connected to a single input on SFP101, in a lowest-

cost implementation, its resistance to ESD is much

lower than the “remote” circuit. High ESD resistance

is not required for temperature sensing of the shunt,

as the ESD transients will be absorbed and bypassed

by the shunt itself. However, if the “on-board” therm-

istors’ measurement circuit is used for other tasks, it is

possible to safeguard the IC and related components

by inserting appropriately large resistors in series with

input and switch-control lines, as well as by adding

transient protectors for the switches. The number of

the sensors (thermistors) can also be increased; please

contact Sendyne for details.

Linearization of the “on-board” thermistors is done

with exactly the same method as the “remote” therm-

istor, by connecting a reference/linearization resistor

in parallel to the sensor. There are also two measure-

ments required in order to calculate the value of

parameter Y for each “on-board” thermistor.

0

1

2

3

4

5

6

7

8

9

10

0

20

40

60

80

100

120

140

160

180

200

-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120

Line

ariz

ed R

esis

tanc

e, kΩ

Res

ista

nce,

kΩ

Temperature, °C

Thermistor resistance

Linearized resistance

Figure 15: Resistance vs Temperature


Sendyne SFP101EVB

However, since the reference resistor is time shared

between all the “on-board” thermistors, there is only a

single measurement for the reference resistor, and one

measurement for each “on-board” thermistor.

In operations, firstly all switches except the reference

resistor switch are opened; the voltage differential be-

tween pins 12 and 13 is digitized; this is the measure-

ment related to the reference/linearization resistor.

Then, while the reference resistor switch is still closed,

one of the “on-board” thermistor’s switches is also

closed; the voltage differential between pins 12 and

13 is again digitized; this is a measurement related

to the specific “on-board” thermistor. This process is

repeated for each “on-board” thermistor in turn.

All of these A/D measurements are ratiometric, i.e.

the excitation voltage of the “on-board” thermistors’

circuit (AVDD) is also the reference for the A/D; the

exact value of this excitation voltage does not mat-

ter, as long as it is stable between the time when the

reference resistor is measured, and the time when any

one thermistor is resolved. From the four (4) measure-

ments (one for the reference resistor, and one each

for the “on-board” thermistors), the Y parameters are

calculated.

Calculation of Y is a little more difficult in the case of

the “on-board” thermistors, as the current through

the circuit when evaluating the reference resistor and

while measuring each thermistor is not the same;

however, a linear-circuit DC calculation allows deriva-

tion of a simple formula for computation of Y, namely:

[9]

where ADCREF and ADCTH are the two measurements

– one for the reference resistor and another for any

particular “on-board” thermistor (in parallel to the

reference resistor); these are the A/D results ex-

pressed as a number between 0 and 1; in other words,

the actual voltage between pin 12 and pin 13 for these

measurements is the reference voltage of the A/D

(equal to AVDD) times the ADC value (that is between

0 and 1).

|| *(1 )*(1 )

TH REF TH REF

REF REF TH

R R ADC ADCYR ADC ADC

−= =

−

×1

×1

×1

TEMPERATURE SENSING

SW

AGND

ADC2

4.99k

1k

1k t

10k

42

41

40

39

AVDD

10.0k

5k

10k

AVDD

AGND

SW

10.0k

13

12

18

27

28

t

SW SW SW

t t

Thermistor

Selection

Controls

REMOTETHERMISTOR

LOCALTHERMISTORS

VREF

24

AVDD

23

AGND

Figure 16: Measurement of Remote Thermistor


Sendyne SFP101EVB

×1

×1

×1

TEMPERATURE SENSING

SW

AGND

ADC2

4.99k

1k

1k t

10k

42

41

40

39

AVDD

10.0k

5k

10k

AVDD

AGND

SW

10.0k

13

12

18

27

28

t

SW SW SW

t t

Thermistor

Selection

Controls

REMOTETHERMISTOR

LOCALTHERMISTORS

VREF

24

AVDD

23

AGND

For determination of the temperature for both “re-

mote” and “on-board” thermistors, first the resistance

of the sensor is calculated from its Y value, and then

(for example) the Steinhart-Hart equation is used for

calculation of the temperature from the thermistor’s

resistance.

The actual resistance of any thermistor is calculated

from parameter Y (and using the fixed reference resis-

tor value) as follows:

[10]

The Steinhart-Hart equation for calculation of the

temperature from the thermistor’s resistance has a

form of:

[11]

where T is the absolute temperature in Kelvin (°C +

273.15); R is the resistance of the thermistor in Ohms;

C1, C2, and C3 are the Steinhart-Hart coefficients.

Please note that the natural logarithm value ln(R) can

be calculated only once; it is used with C2 directly, and

with C3 raised to the 3rd power.

Typically, the thermistor manufacturer can supply

Steinhart-Hart coefficients, or they can be calculated

from the resistance vs. temperature data for a particu-

lar type of thermistor.

For example, the thermistors used as “on-board”

sensors on the SFP101EVB evaluation board have the

following Steinhart-Hart coefficients:

C1 = 8.588600E-04, C2 = 2.565500E-04, and

C3 = 1.701100E-07.

Temperature Measurement ReportingThe SFP101 reports the measured values for the tem-

perature measurements as the averaged quantity over

fixed interval of 240 ms.

The measured value is reported in response to a

request by a Host controller (or a PC that is executing

Sendyne’s control software application).

If elapsed time between the data requests is less than

*1 11

REF REFTH

R R YRY

Y

= =−−

( ) 31 2 3

1 * ( ) *[ln ]C C ln R C RT= + +

Figure 17: On-board Thermistors Interface


Sendyne SFP101EVB

240 ms, the reported amount will likely be a repeat of

the same (unchanged) value. Note that unlike current

and voltage measurements, the TEMP_S: ADC Tem-

perature Status register does not provide a Data Read

Repeated flag bit; it is not required.

The Y values for one Remote and three Onboard

thermistors are provided, respectively, at the registers

TEMP0_R_OUT: Remote Temperature Measurement

Registers, TEMP1_OB_OUT: Onboard Thermistor 1

Registers, TEMP2_OB_OUT: Onboard Thermistor 2

Registers, and TEMP3_OB_OUT: Onboard Thermis-

tor 3 Registers; all contain 24-bit binary numbers,

representing the Y values between 0 and 1.

In order to calculate the temperatures, simply divide

the amounts in the corresponding Y value registers

by 224; then calculate the resistance of each thermis-

tor (using 10000 Ω as the reference resistor value, per

Equation 10), and apply Equation 11 described in the

Temperature Measurements section above.

Temperature Reporting in Degrees CelsiusThe user can always get the thermistor measurement

data that is related to the thermistors’ resistances, and

implement calculations of the temperature in the Host

using any suitable algorithm.

Alternatively, if median characteristics of the therm-

istors are known, it is possible to create and upload

to the SFP101 IC the translation (look-up) tables for

direct read-out of the temperatures in degrees Celsius

(derived from Y values described previously in this

document). In this case, the Host controller is relieved

of any complicated temperature calculations, thus

freeing the Host for other tasks, or reducing the Host’s

energy consumption.

There are two independent tables - one for “external”

thermistor, and another for “on-board” thermistors;

these two tables can have different data to accommo-

date different characteristics of the thermistors.

Resolution and accuracy of translation for tables is

very high, with effective calculation errors that are less

than 0.5 m°C.

If automatic temperature compensation of the shunt’s

resistance is enabled, then the SFP101 IC must have

a Celsius translation table for the “on-board” thermis-

tors.

Please contact Sendyne for information on creating Y-

to-Celsius translation tables for custom thermistors.

The Celsius temperature values for one Remote and

three Onboard thermistors are provided, respectively,

at the registers TEMP0_R_C: Remote Sensor Celsius

Data, TEMP1_OB_C: Onboard Thermistor 1 Celsius

Data, TEMP2_OB_C: Onboard Thermistor 2 Celsius

Data, and TEMP3_OB_C: Onboard Thermistor 3

Celsius Data; all of these contain 24-bit signed 2’s

complement numbers, with one count of the most-

significant byte representing a value of 2 °C. In order

to calculate the Celsius temperature from any of the

above registers, simply divide their value by 215.


Sendyne SFP101EVB

The following descriptions of the circuits that include

specific reference designators are referring to the

schematics of the module starting on page 74.

EMI/RFI FiltersThe two low-pass filters for the two independent

channels of the current measurement system are

implemented with passive RC circuits. They provide

both common-mode rejection for the high-frequency

RF signals, and differential-mode attenuation used for

reduction of signal bandwidth prior to amplification

and digitization by the A/D (anti-aliasing).

While a passive circuit cannot approach the filtering

effectiveness of a circuit with active components (e.g.

OpAmps), the passive technique provides extremely

high performance in regard to linearity, even in the

presence of high-level interference. A circuit with any

active components would likely be severely disturbed

or even destroyed by signals and transients that can be

normally processed by a passive filter.

Using power-electronics parlance, each of the two

filters has two low-valued high-frequency attenuating

Y capacitors (C13/C14 and C15/C16), and one larger-

valued X capacitor (C11 and C12) used for anti-alias-

ing of the ADC inputs.

DriversThe MOSFET switches at the inputs of the current-

measurement system require defined voltages in order

to be in the fully-on and fully-off states. At the same

time, when one of the channels is changing its mode

from normal operations to calibrations and vice versa,

it is important that the two switches associated with

that particular current-processing channel are never

turned on at the same time. If they are turned on at

the same time, it will create a disturbance at the input

of the other current-processing channel that is provid-

ing the measurement data to the Host.

For this reason, the driver circuit for the input

switches operates by way of the so-called break-

before-make principle; it is providing non-overlapping

turn-on signals to both MOSFET switches associated

with a single channel that changes its mode.

Components D2/R31 and D3/R33 provide this func-

tionality together with U6 and U7 that level-shift and

amplify the switch-control signal from the SFP101.

Isolated DC/DC ConverterPower circuits that benefit from the application of

SFP101EVB, by design, have large operating currents.

Under these conditions, it is almost impossible to pro-

vide a stable and noise-free ground or common-refer-

ence voltage. Often, nodes called “Ground” throughout

the circuit will have wildly different voltage potentials.

This will upset the accuracy of any precision measure-

ment device. This is but one reason why the SFP101E-

VB utilizes an isolated DC/DC converter for its power

supply. The other reasons include: the inherent safety

of having an isolated measurement system, without

regard to the actual voltage difference between the

resistive shunt and the “ground” potential, with the

ability of making “high-side” current measurements;

as well as the highest linearity and low-noise perfor-

mance of the analog front end.

The isolated DC/DC converter is constructed with U3,

a Schmitt trigger IC, utilized as an approximately

188 kHz near-50 % duty cycle square-wave oscillator,

followed by an integrated full-bridge driver U4 that

provides bidirectional square-wave drive to the isola-

tion transformer L2. Capacitor C5 prevents saturation

of the transformer’s core due to DC current (when the

duty cycle of the oscillator is not exactly 50 %, then an

effective average DC current will flow through the pri-

mary winding of the transformer, eventually saturat-

ing the ferrite core).

The full-wave rectifier D1, a dual-diode component,

processes the voltage on the secondary windings of the

transformer. Rectifier D1 is specifically a “standard”

silicon (non-Schottky) diode that is able to operate

Support Circuit Implementation


Sendyne SFP101EVB

over large temperature range with low

leakage currents.

The unregulated rectified DC voltage is filtered by

bypass capacitor C2 and further smoothed by the

RC filter R3/C6, supplying the highest voltage in the

circuit, nominally 3.2 V to 4.5 V.

This voltage is used directly by the drivers for the

MOSFET switches at the inputs of the current-

measurement system, and processed by a low-power

voltage regulator U1 for the rest of the isolated circuit,

including the digital and analog supply rails of the

SFP101 IC.

The user is reminded that the isolated DC/DC convert-

er in the SFP101EVB is a low-power circuit; the whole

module including the DC/DC converter consumes less

than 17 mA of current from a +5 V supply (typically

provided by the USB port on the PC).

Power Conditioning and FilteringA micro-power Low Dropout (LDO) voltage regula-

tor U1 reduces the filtered DC voltage from DC/DC

converter to the nominal supply voltage of +2.50 V

±0.4 % at 25 °C (+2.50 V ±3 % over the full operating

temperature range of –40 °C to +125 °C).

This voltage is used directly for the ISOVDD (digi-

tal supply rail for the SFP101 IC); after additional

filtering by L3/R32/C9 the same voltage powers the

ISOAVDD, the supply rail for the analog portion of

the IC. Because of the voltage drop on R32, the analog

supply voltage is slightly lower (by 50 mV to 75 mV)

than the digital supply ISOVDD.

The user should be aware of the non-obvious “reverse”

functionality of the filter L3/R32/C9. It prevents

pulses of current consumption in the analog part of

the circuit from reaching and disturbing the output of

the voltage regulator. Being a micro-power IC, regula-

tor U1 cannot provide high performance in respect to

voltage regulation under conditions of load transient

currents; furthermore, its transient response changes

as the ambient temperature changes. These voltage

disturbances are very small (sub millivolt amplitude),

and cannot be readily observed with any measuring

instruments. In addition, the voltage transients caused

by the analog supply currents are totally obscured by

the noise produced in the digital rail of the IC.

However, in contrast to the disturbances caused by

the digital part of the circuit, the transients from the

analog supply rail are synchronous to the sampling

frequency of the A/D, and affect the measured values

with a systematic error (unlike the digital-induced

part that manifests itself as near-Gaussian random

noise that will be averaged out by the filtering action

of the ΣΔ ADC).

Inconveniently, even for a device having very high

Power Supply (noise) Rejection Ratio (PSRR) of

65 dB typical, such as the SFP101, the millivolt supply

variations on the analog rail translate into 500 nV

variations referred to the input; for an IC that operates

with single-nanovolt resolution and precision, the

½ µV interference is indeed a large one.

A very simple filter created by L3/R32/C9 completely

eradicates any interactions between the noise on the

supply rails and the measured values.

In some applications, it may be beneficial or conve-

nient to utilize two independent voltage regulators,

one for the digital and another for the analog supply

rail; however, the same filtering circuit as created by

L3/R32/C9 is strongly recommended for application

at the output of the regulator for the analog supply.

Logical Level Shifters and Isolated CommunicationsThe galvanically-isolated front-end circuit powered

by the isolated DC/DC converter communicates with

the Host using a digital isolator with two independent


Sendyne SFP101EVB

channels – one transferring the data in the forward

direction, and another in reverse direction.

On the un-insulated side (connected to the Serial-to-

USB cable or to the Host), the supply voltage for the

digital isolator IC U2 is the same as the supply voltage

for the whole module, +5.0 V ±10 %.

On the isolated side, the supply voltage for the digital

isolator is the unregulated filtered voltage ISOFHV,

nominally +3.2 V to +4.5 V.

At the same time, the supply rails for the SFP101

IC are near +2.5 V; clearly, some level translation is

required between the digital input and output of the

asynchronous serial communications channel on the

SFP101 IC and the I/O of the digital isolator.

This translation is provided by the component Q1,

with a simple and cost-effective implementation for

the adjustment of the required input / output voltage

levels between the parts of the circuit operating with

different supply voltages.

An atypical feature of this circuit is that signal-driving

output from U2.2 is connected to the Drain of the

translating NMOS transistor, and the corresponding

input signal AFERXD on the SFP101 IC is connected

to the Source of the same transistor.

In operations, when the output U2.2 starts to tran-

sit from High to Low state, the Drain of the NMOS

transistor follows the change. When this voltage is one

diode drop below the level of ISOVDD, the body diode

of the NMOS transistor starts to conduct the current,

and the voltage on the Source of the NMOS transistor

(connected to R4) begins to fall. Also, when drain volt-

age is 0.5 V to 0.9 V below the level of ISOVDD, the

NMOS transistor turns on (due to enhancement volt-

age between the Gate and Drain that creates the same

result as the voltage between the Gate and Source).

When the output U2.2 reaches the lowest level close to

the potential of ISOVSS, the voltage on the AFERXD

net is essentially the same due to NMOS transistor

being fully on.

On the positive-going transition of U2.2 the same

sequence of events occurs in the opposite order.

An important attribute of these operations is the fact

that at the times when the AFERXD digital input

transitions through its logic-switching threshold, the

transition is fast and noise-free due to the “fully on”

state of the NMOS transistor.

When output U2.2 is at the high voltage level, the po-

tential on the AFERXD net is controlled by the pull-up

action of R4; it is effectively the same as the voltage on

supply rail ISOVDD.

The translator operating in the opposite direction,

from the AFETXD output to the U2.3 digital input

on the digital isolator, is working, perhaps, in a

more traditional way; it could be characterized as a

common-Gate voltage amplifier with Source input;

this well-known configuration provides only voltage

amplification, and no current gain.

Once again, at the times when U2.3 input transitions

through its logic-switching threshold, the transition

is fast and noise-free due to the “fully on” state of the

NMOS transistor. When the input at U2.3 reaches a

level of approximately 2 V, the corresponding NMOS

transistor switches off, and the additional increase of

the voltage at U2.3 is produced by the pull-up action

of R5. This part of the transition may be much slower

than the transition through the switching threshold;

however, by this time the changeover has already hap-

pened and slower rise-time will not influence the logic

level at U2.3 or create any noise instigating condi-

tions.


Sendyne SFP101EVB

Serial InterfaceAn asynchronous serial interface (UART) provides ac-

cess to the internal registers of the SFP101 via the Rx

and Tx lines. Data format is 8 data bits, no parity, and

1 stop bit; see Fig. 18.

While the SFP101 is capable of full-duplex operations

(simultaneous and unsynchronized transmission and

reception of data), it is intentionally restricted to half-

duplex interrogate/respond operations by the com-

munications protocol. With a suitable driver/receiver,

both transmit and receive lines can be consolidated

into a single-wire bidirectional LIN-like serial com-

munications interface.

Baud Rate SelectionThe SFP101 supports several baud rates. After a

Power on, reset the Baud Rate defaults at 19,200. The

Baud Rate can be changed by the baud rate selection

bits (BAUD_SEL) of the COM_C register.

Baud Rates Supported by SFP101

Baud Rate Actual % Error9600 9598.55 -0.015 %

19,200 (default) 19,203 +0.016 %

115,200 115,218 +0.016 %

Cyclic Redundancy Check CRC-8In a message frame, the CRC-8 is calculated over the

whole message during both read and write operations.

The CRC polynomial used is X8+X2+X1+X0. The

CRC-8 will detect all single bit errors, all odd number

of bit errors, any burst error less than 8 bits long and

most of other types of errors. (The CRC-8 code is part

of the SMBus specification 1.1 and information on its

implementation as well as a CRC-8 calculator can be

found at www.SBS-forum.org.)

Register AddressingRegisters of the SFP101 are memory-mapped. They

can be accessed individually or in groups of two, three,

or six consecutive bytes.

Register GroupsThe registers are grouped into four main categories:

General Purpose Registers

These registers control or provide status information

for SFP101 general functions, such as power manage-

ment, communication setup, etc. This group also

includes Flash Interface registers that provide access

to the user-definable and permanently-stored look-up

tables.

Current Acquisition Related Registers

These registers provide current ADC data as well sta-

tus and control information.

Voltage Acquisition Related Registers

These registers provide voltage ADC data and status

information.

Temperature Acquisition Related Registers

These registers provide temperature ADC data and

status information.

Communications

Byte field

LSB (bit 0)

MSB (bit 7)

Start bit

Stop bit

Figure 18: Byte Field Structure


Sendyne SFP101EVB

Message FramesAccess to the registers of the SFP101 is accomplished

through polling by the host. Data from the host or the

SFP101 are encapsulated in message frames (depicted

in Fig. 19) that are themselves consisting of individual

byte fields (shown in Fig. 18). Each message frame

includes a Header transmitted by the host, followed

by either Parameters supplied by the host for a write

operation, or Response Data provided by SFP101 for a

read operation.

Frame HeaderThe Frame Header consists of the Mode Byte and the

Register Address Byte. The Mode Byte contains in-

formation on whether it is a read or a write operation

and the number of bytes to be sent in the Parameters

field during a write operation or to be received in the

Response Data field during a read operation.

The Register Address Byte contains the address of the

register to be either written or read. For multi-byte

register operations the Register Address Byte should

be pointing at the lowest address of the multi-byte

register. If the Register Address Byte does not point

at the lowest address of a multi-byte transfer request,

the command, whether a “read” or “write”, will not be

executed and the SFP101 will set the communication

error flag. Details for the Frame Header are shown in

Figure 19.

Communications With a Host

Write RegistersAll data transfers are initiated by the host. Transfers

from the host to the SFP101 can be 1, 2, 3, or 6 bytes

long, without including the CRC-8 byte. After a write

operation into the SFP101, the host should read back

the contents of the target registers in order to verify

that the operation completed successfully without any

errors.

Any detected error will cause the SFP101 to discard

the message and upon detection set the COM_ER

bit of all the Group Status Registers (GP_S, CUR_S,

VOLT_S and TEMP_S).

During a multi-byte transfer, the Register Address

Byte contains the first address (lowest) of the Regis-

ters to be read or written.

Data bytes following the Message Header (Mode and

Register Address Bytes) are arranged in the little-en-

dian format, with the least significant byte immediatey

following the Register Address Byte.

A CRC-8 byte, calculated upon the whole message,

needs to be appended to the end of the packet.

Message Frame

Header Parameters or Response

Mode Field Address Field Data Field(s) Data Field Data Field

Intra-frame response space Inter-byte space

CRC-8

Interframe distance

MSBLSB

Figure 19: Message Frames


Sendyne SFP101EVB

Read RegistersThe host can request to read the contents of a register

with a Read command specifying the number of bytes

to be read, followed by the address of the register (the

address of LSB for multiple registers). The SFP101

will respond with a packet headed by the relevant

Register Group Status byte (XXX_S - GP_S, CUR_S,

VOLT_S, or TEMP_S). The two most significant bits

of the Status Registers contain the ID of the group and

can be used as an aid for packet synchronization. In

addition, the Register Group Status byte provides the

host with various error statuses.

The Register Group Status byte will be followed by

one to six bytes of requested data. This data is also ar-

ranged in the little-endian format, with the least

significant byte immediately following the XXX_S

byte. Finally a CRC-8 code, calculated upon the whole

message will be appended at the end of the packet.

For example, a read request for any Status Register

will return three bytes: two XXX_S bytes and a CRC

byte.

Read and Write Multiple RegistersIt is possible to read or write to multiple multi byte

registers in one transaction. For example, a six byte

read could read two consecutive three-byte register

sets at once. For writes, all multi-byte registers must

fit exactly into the specified number of bytes for the

transaction. The Register Address Byte must contain

the first (lowest) address of all the multi-byte registers

to be read or written. The addresses must be continu-

ous across both multi byte registers, and cannot have

any gaps in between. The transaction is invalid if any

of the addresses do not exist.

Communication Errors When the SFP101 detects a communication error it

will ignore the transaction that caused the error and

set COM_ER bit in the XXX_S register of every group.

The COM_ER bit is cleared for all XXX_S registers

after a read operation. The following conditions will

cause the SFP101 to set the error flag COM_ER:

CRC-8 error

Cyclic Redundancy Check data provided by the

host does not match the contents of the last

communication.

Non-existing address

A Read or Write operation to a non-defined address.

Mismatch between transfer type

and accompanying data

A multi-byte register Write operation is not

accompanied by the specified number of bytes.

Address boundary violation

A multi-byte transfer start address does not point

to the lowest address of the multi-byte register.

Timeout

A write operation times-out before all expected data

are received.

Failure to read back baud rate register

The COM_C register is not read back after being

written to.

Performance & TimeoutInter-byte space

It is desirable that the total maximum space between

the bytes of a frame will not contribute more than

40% additional duration as compared to the nominal

transmission time.

The nominal transmission time depends on the se-

lected baud rate. For example, at 115 Kbs the bit dura-

tion is approximately 8.7 μs and the byte transmission

time is 87 μs. A frame with 9 bytes will have a nominal

transmission time of 783 μs. The maximum total

space between bytes (not including the Inter-frame

response space) should be less than 313 μs.

Whenever possible, the SFP101 will observe this tim-

ing restriction, but it will not reject frames if they are

longer than the maximum frame space.


Sendyne SFP101EVB

Intra-frame response space

The maximum time the host should wait between the

end of the transmission of a Read request Header and

the start of the response of the SFP101 is 20 ms. If the

SFP101 has not responded by then, a new transmis-

sion may be started.

Intra-frame Timing

Parameter Description Timeout(ms)

TFRAME Time for transmission of a

Message Frame

20

A message reception will be aborted by the SFP101

after occurrence of a TFRAME timeout.

ADC Sampling Rate and Data Read-OutAll ADC channels rely on the same clock to acquire

data but they are multiplexed and interleaved to ac-

quire data at different frequencies.

The relationship of the sampling frequencies among

the three ADC channels is given in the following table:

ADC Channels Sampling Rate

Base Frequency

CurrentADC

VoltageADC

Temperature ADC

400 Hz 400 Hz 400 Hz 4.1667 Hz

Data Averaging for Current and Voltage

Because the sampling rate and the communications

are asynchronous, a read report for a current or volt-

age value is an average of all the samples acquired

since the last read report for that channel. This allows

the SFP101 voltage and current data to be read at any

rate without losing accuracy.

If the host performs a read operation before a new

sample is acquired, the D_RPT flag of the relevant

status register will be set to indicate that the data read

was repeated and the same data will be sent again.

The maximum rate at which new read reports can be

obtained is the sampling rate of the channel.

Data Averaging for Temperatures

The values in the temperature registers are an average

of all readings acquired for each of the thermistors

over 240 ms. The temperature registers do not have a

data repeat flag.

Figure 20: Frame Header

[7][2:6] [0:1]

R/W Sn

R/W=Read/Write Data 0: Write Data

1: Read Data

Sn = Transfer Type b1 b0

0 0: 1 byte 0 1: 2 bytes 1 0: 3 bytes 11: 6 bytes

Mode Byte

[0:7]

Register Address Byte

Register Address Byte

Data Reserved (set to zero)

Header Header


Sendyne SFP101EVB

Access to Flash TablesIn order to simplify computational load in the Host,

and enable temperature compensation of the shunt’s

resistance, the SFP101 utilizes quick look-up tables in-

stead of complicated analytical calculations. Namely,

look-up tables are used for translation of the Y values

(see the section on Temperature Measurements) from

thermistors into temperatures expressed in degrees

Celsius, and for (shunt) Resistance Temperature De-

pendence Table (RTDT).

The IC contains four (4) FLASH tables, 1 kB each.

Every table consists of 256 entries, each entry is 32

bits (4 Bytes) long. Selection of an individual table

is controlled by the FLASH Table Number register

F_TABLE (address 0x2D), and a particular entry in a

table is pointed to by the FLASH Entry Number regis-

ter F_ENTRY (address 0x2C).

FLASH Tables’ Utilization

Table Number

Table Utilization

0 Y-to-Celsius conversion for

“on-board” thermistors

1 Y-to-Celsius conversion for

“external” thermistor

2 RTDT compensation for

shunt resistance

3 Reserved

All of the tables will typically be either initialized at

the factory, or loaded during factory or the user’s

calibration; the user should not need to access them

during normal operations. As a matter of fact, it is not

possible to erase and/or write data into these tables

during the normal operations. In order to update a

table, the IC has to enter a special mode, controlled by

the FLASH write/erase enable bit (F_WE_EN) in RST

register (address 0x10, bit 1); normal measurement

activities stop during this special mode of operations.

This mode of operations is utilized only for tables’

update during calibrations or special initialization of

the SFP101.

AddressMode Byte Data (LSB) Data (MSB) CRC-8

AddressMode Byte

XX Data (LSB) Data (MSB) CRC-8XXX_S

One to six bytes

One to six bytesRegister GroupStatus Register

Register Group ID(b7b6 of Status Reg.)

00-General01-Current ADC10-Voltage ADC11-Temperature ADC

Write Registers

Read Registers

Figure 21: Write/Read Registers


Sendyne SFP101EVB

Erasing a table and providing write access:

a. Set FLASH write/erase enable bit (F_WE_EN) in

RST register (address 0x10, bit 1).

b. Write the appropriate Table Number and specifi-

cally Entry Number 0 into F_TABLE and F_ENTRY

registers (0x2D, 0x2C), using 2-Byte write transfer

starting at F_ENTRY (0x2C).

c. Write the value 0x55 into F_ERASE_L (address

0x2E), and the same Table Number as used in step b.

above into F_ERASE_H (address 0x2F), using 2-Byte

write transfer starting at F_ERASE (0x2E); wait 50 ms

for ERASE to complete.

d. Verify erasure by reading F_ERASE register, using

2-Byte read transfer starting at F_ERASE (0x2E).

F_ERASE_L will return the number 0x55, and F_

ERASE_H will return the Table Number (0-3) of the

table just erased. If no table was erased, the return

value will be 0xFF55.

Writing to a table (immediately after performing the

Erase operation):

a. Write a single 32-bit table entry using 6-Byte access

starting at F_DATA_0 (0x28), specifying Table Num-

ber (equal to the last table erased), Entry Number

(typically starting at 0), and 32-bit FLASH data; all in

a single 6-Byte transfer.

b. Repeat a. (continue writing to the subsequent en-

tries) until the table is filled (Note: the Entry Number

must be different for every 6-Byte write transfer).

After write operations for a table are completed, the

SFP101 should be reset or the power should be cycled,

in order to return to normal operations.

Reading table entries sequentially:

a. Initialize the Table Number register F_TABLE

(address 0x2D) to point to the appropriate table and

enable the READ_INC bit in the same register; set

Entry Number register F_ENTRY (address 0x2C) to

the initial entry (typically 0), using 2-Byte write access

starting at F_ENTRY (0x2C).

b. Read the Table Number, Entry Number, and

FLASH data together using 6-Byte read access starting

at F_DATA_0 (0x28) (Note that READ_INC bit in

register F_TABLE will be reported as set).

c. Since the Entry Number will be automatically

incremented after the completion of each 6-Byte read

access, simply repeat step b. to read the entire table.

Reading table entries randomly:

a. Initialize the Table Number register F_TABLE

(address 0x2D) to point to the appropriate table and

clear the READ_INC bit in the same register; set

Entry Number register F_ENTRY (address 0x2C) to

the required entry, using 2-Byte write access starting

at F_ENTRY (0x2C).

b. Read the Table Number, Entry Number, and FLASH

data together using 6-Byte read access starting at

F_DATA_0 (0x28) (Note that F_TABLE. READ_INC

will be reported as cleared).

c. Repeat steps a. and b. to read the required table

entries.

Information complementary to the discussion above is

provided in the Registers section, within the descrip-

tions of the individual FLASH interface registers.


Sendyne SFP101EVB

Address

Write 2 bytes

DataL CRC-8

CUR_S

Write 0x03E8 into Shunt Calibration Data Register SHNT_CAL

Read back SHNT_CAL

Mode byte

0x01 0x41

SHNT_CAL

0xE8 0x03

AddressMode byte

0x81 0x41

Read 2 bytes SHNT_CAL

0x40 0xE8

CRC-8

0x03

SHNT_CALL

CUR_S

Read Current Measurement Data Output Registers CUR_OUT

AddressMode byte

0x82 0x32

Read 3 bytes CUR_OUTL

0x40 0x04 0x30

CUR_OUTL

0x00

CRC-8

0xE5

CUR_OUTM CUR_OUTH

TEMP_S

AddressMode byte

0x83 0x90

Read 6 bytes TEMP1_OB_OUTL

0x80 0x00 0x8C

TEMP1_OB_OUTL

0x84

0x00 0x4C 0x85

CRC-8

0xE0

TEMP1_OB_OUTM TEMP1_OB_OUTH

Read on-board Sensor Temperature Data Registers TEMP1_OB_OUT and TEMP2_OB_OUT

From Host

From SFP101

LEGEND

DataH

0x19

SHNT_CALH

0x1C

TEMP2_OB_OUTL TEMP2_OB_OUTM TEMP2_OB_OUTH

Figure 22: Examples of Communication


Sendyne SFP101EVB

Registers

Figure 23: Register Map

The SFP101 contains a set of user accessible registers. Registers can be single or multi-byte. The registers and their

functions are described in the following sections. The units are given in ADC counts, which are a mapping of the ADC

voltage to a 24 bit value.

GP_S0x00 CUR_S0x30 VOLT_S0x50 TEMP_S0x70

COM_C0x01

CUR_C0x31 VOLT_C0x51 TEMP_C0x71

GENERAL PURPOSE

CURRENT MEASUREMENT

CURRENTMEASUREMENT,CONTINUED

VOLTAGEMEASUREMENT

TEMPERATUREMEASUREMENT

CURRENT CONTROL& STATUS

FLASHINTERFACE

FLASH DATA

FLASH ENTRY

VOLTAGE CONTROL& STATUS

TEMPERATURE CONTROL & STATUS

CUR_ACC00x35

CUR_ACC10x36

CUR_ACC20x37

CUR_ACC30x38

CUR_ACC40x39

CUR_ACC50x3A

COULOMB COUNTING DATA

VOLT_CALL0x55

VOLT_CALH0x56

VOLTAGECALIBRATION DATA

VOLT_GCCL0x57

VOLT_GCCH0x58

VOLTAGE GAIN & CALIBRATION CONTROL

F_DATA_00x28

F_DATA_10x29

F_DATA_20x2A

F_DATA_30x2B

F_ENTRY0x2C

FLASH TABLE

F_TABLE0x2D

FLASH ERASE

F_TABLE_L0x2E

F_TABLE_H0x2F

SHNT_CALL0x41

SHNT_CALH0x42

SHUNTCALIBRATION DATA

CUR_GAIN0x43

CURRENTGAIN CONTROL

COMP_CTRL0x44

COMPENSATIONCONTROL

C_TRESH_L0x45

C_TRESH_M0x46

C_TRESH_H0x47

CHARGETHRESHOLD VALUE

D_TRESH_L0x48

D_TRESH_M0x49

D_TRESH_H0x4A

DISCHARGETHRESHOLD VALUE

CHARGE_ACC00xC0

CHARGE_ACC10xC1

CHARGE_ACC20xC2

CHARGE_ACC30xC3

CHARGE_ACC40xC4

CHARGE_ACC50xC5

CHARGE_ACC60xC6

CHARGE_ACC70xC7

ACCUMULATEDCHARGE DATA

DIS_ACC00xC8

DIS_ACC10xC9

DIS_ACC20xCA

DIS_ACC30xCB

DIS_ACC40xCC

DIS_ACC50xCD

DIS_ACC60xCE

DIS_ACC70xCF

ACCUMULATEDDISCHARGE DATA

RST0x10

CUR_OUTL0x32 VOLT_OUTL0x52 TEMP0_R_OUTL0x72

CUR_OUTM0x33 VOLT_OUTM0x53 TEMP0_R_OUTM0x73

CUR_OUTH0x34 VOLT_OUTH0x54 TEMP0_R_OUTH0x74

CURRENT DATA

RESET

VOLTAGE DATAREMOTE SENSORTEMPERATURE DATA

GENERAL PURPOSESTATUS

COMMUNICATIONS

TEMP1_OB_OUTL0x90

TEMP1_OB_OUTM0x91

TEMP1_OB_OUTH0x92

ON-BOARD SENSORSTEMPERATURE DATA

TEMP0_R_CL0x99

TEMP0_R_CM0x9A

TEMP0_R_CH0x9B

REMOTE SENSORCELSIUS DATA

TEMP1_OB_CL0x9C

TEMP1_OB_CM0x9D

TEMP1_OB_CH0x9E

TEMP2_OB_CL0x9F

TEMP2_OB_CM0xA0

TEMP2_OB_CH0xA1

TEMP3_OB_CL0xA2

TEMP3_OB_CM0xA3

TEMP3_OB_CH0xA4

ON-BOARD SENSORSCELSIUS DATA

TEMP2_OB_OUTL0x93

TEMP2_OB_OUTM0x94

TEMP2_OB_OUTH0x95

TEMP3_OB_OUTL0x96

TEMP3_OB_OUTM0x97

TEMP3_OB_OUTH0x98

PNS_10x11

PART NUMBERSTRING 1

PNS_60x16

MC_L0x21

MANUFACTURINGCODE

0x22

MC_H0x23

VER_L0x26

VERSIONCODE

PN_L0x24

PART NUMBERCODE

0x25 PN_H

MC_M

VER_H0x27

CUR_ACC60x3B

CUR_ACC70x3C

Read only

Read/write

Read /write non-volatile

Addresses printed in Bold indicatethe initial address to be used forblock transfers

PNS_70x17

PART NUMBERSTRING 2

PNS_120x1C

SerNo_0

SerNo_1

0x1E

0x1F

SERIAL NUMBER

SerNo_20x20

*


Sendyne SFP101EVB

General Purpose RegistersThe General Purpose Registers control the general

configuration of the SFP101, as well as provide infor-

mation such as hardware and software version, manu-

facturing codes, etc. that can be used for diagnostic

purposes by higher level protocols.

General Purpose StatusThe General Purpose Status register GP_S is a read

only register containing the Group identification bits

and error information pertaining to the last commu-

nication.

The GP_S register is always attached as a header to

SFP101 read responses for addresses 0x00 to 0x2F.

GP_S: General Purpose Status (Address: 0x00)

Bit Bit Symbol Bit Description[7:6] ID R 00: General Purpose

Registers Group ID

[5:1] Reserved; always reads

as zero

[0] COM_ER R 1: Communication Error

0: No Error

Communication ControlThe Communication Control register COM_C controls

the mode of communication of the SFP101 through

the serial port.

Through the COM_C register the host can program

the serial port baud rate and reset the communication

channel.

COM_RST: Communication Reset

Setting this bit to one clears all volatile registers, and

returns all peripherals into their default status, includ-

ing the baud rate (19,200.) Non volatile registers do

not reset.

COM_C: Communication Control & Status

(Address: 0x01)

Bit Bit Symbol Bit Description[7:3] Reserved

[2] COM_RST W 1: Reset

[1:0]

BAUD_SEL

R/W

00: 9600

01: 19,200(default)

10: 115,200

11: Reserved

After Setting the BAUD_SEL bits the host must per-

form a Read Register operation on COM_C register

at the old baud rate to verify that the values are

accepted. The SFP101 will switch baud rates after

the completion of the Read operation. If this Read

Register operation is not carried out, the SFP101 will

remain at the old baud rate and set the COM_ER bit.

Reset IC and Write/Erase Control for FLASH TablesSetting of the RST bit is equivalent to a power-on reset

of the IC. It clears all volatile registers

and returns all peripherals into their default status,

including the baud rate (19200.) After setting

this bit, communications will be disabled for 600 ms

max. Non-volatile registers are not affected

by the reset.

Bit F_WE_EN of the RST register controls FLASH

Erase and Write operations. When this bit is

set, the IC stops normal functions (such as sampling

of current, voltage, and temperatures). After

the FLASH operations (which are typically erasure

and writing of the FLASH tables) are finished,

the IC must be reset (or the power must be cycled) in

order to restart normal functioning of the

IC; since all volatile registers will be reset to their

default values, FLASH table write functionality

is not suitable for saving of the accumulated data, or

any data, while the IC is in normal mode of

operations. FLASH Write operations should be

used only for initialization of the IC; however, such


Sendyne SFP101EVB

initialization may occur both at the initial testing and

calibration, and when the IC is already

assembled into the end-user equipment.

RST: Reset (Address 0x10)

Bit Bit Symbol R/W Bit Description[7:3] Reserved

[1] F_WE_EN R/W FLASH Write/Erase

Enable

1: Enable FLASH

Erase and Write

0: Disable FLASH

Erase and Write,

normal operations

[0] RST R/W 1: IC Reset

0: Default, normal

operations

PNS1: 6-Byte (48-bit) Part Number String1Part Number String1 in combination with Part

Number String2 provides alphanumerical Part Num-

ber identification for the IC (e.g. PNS1=”SFP101”,

PNS2=”1ASTZA”).

PNS1: 6-Byte (48-bit) Part Number String1 (ASCII

character codes)

Address Name Register Descrip.0x11 PNS_1 String Byte 1

0x12 PNS_2 String Byte 2





PNS2: 6-Byte (48-bit) Part Number String2Part Number String2 in combination with Part

Number String1 provides alphanumerical Part Num-

ber identification for the IC (e.g. PNS1=”SFP101”,

PNS2=”1ASTZA”).

PNS2: 6-Byte (48-bit) Part Number String2 (ASCII

character codes)

Address Name Register Descrip.0x17 PNS_7 String Byte 7



0x1A PNS_10 String Byte 10

0x1B PNS_11 String Byte 11

0x1C PNS_12 String Byte 12

SerNo: 24-bit Serial NumberIC’s Serial Number or other information.

SerNo: 24-bit Serial Number (binary, uncommitted)

Address Name Register Descrip.0x1E SerNo_0 Serial Number [7:0]

0x1F SerNo_1 Serial Number [15:8]

0x20 SerNo_2 Serial Number [23:16]

Manufacturing Code (Addresses 0x21-0x23)The Manufacturing Code group of three registers con-

tains encoded information for the following fields:

– Manufacturing Date: YYWK

– Location code for Wafer Fab, geometry, assembly,

lot and step

– Revision Code for Silicon and Kernel

Part Number (Addresses 0x24-0x25)The two Part Number registers contain encoded infor-

mation for the SFP101 part number.

Version Code (Address 0x26-0x27)The Version Code register contains information for

the version of the SFP101 firmware.

F_DATA: 32-bit FLASH Table Entry The Four-Byte FLASH data register can only be ac-

cessed as a part of a 6-Byte transfer that also

includes the Table Number and Entry Number regis-

ters, starting at address 0x28.


Sendyne SFP101EVB

Setting the FLASH write/erase enable flag F_WE_EN

in the RST register (address 0x10, bit 1) enables

writing to F_DATA register set, whereas reads can

be made anytime. Writing to this register set will

save the data to the entry specified by the Table

Number and Entry Number registers. When writing,

the Table Number register has to match the value

of F_ERASE_H (the high Byte of the FLASH ERASE

register, address 0x2F).

F_DATA: 32-bit FLASH Table Entry

Address Name Register Descrip.0x28 F_Data_0 Entry Data [7:0]

0x29 F_Data_1 Entry Data [15:8]

0x2A F_Data_2 Entry Data [23:16]

0x2B F_Data_3 Entry Data [31:24]

F_ENTRY: FLASH Entry NumberOne-byte FLASH entry selection register, specifying

one of the 256 entries of a single FLASH table.

F_ENTRY: FLASH Entry Number (Address 0x2C)

Bit Bit Symbol R/W Bit Description[7:0] Entry R/W FLASH Entry selec-

tion, 0 to 255

F_TABLE: FLASH Table NumberOne-byte FLASH table selection register, specifying

one of the four (4) FLASH tables. Also contains a bit

to enable automatic increments of the Entry Number

after every read command. This makes it possible to

read the entire table without having to explicitly incre-

ment the Entry Number.

F_TABLE: FLASH Table Select (Address 0x2D)

Bit Bit Symbol R/W Bit Description[7] READ_INC R/W 1: Enable automatic

incrementing of the

Entry Number reg-

ister after each

read access to the

F_DATA register

set

0: Disable automat-

ic incrementing

[6:3] Reserved

[1:0] TABLE R/W FLASH table selec-

tion, 0 to 3

[00] selects Table 0




F_ERASE: FLASH Erase RegisterFLASH Erase register controls erasure of a FLASH

table in preparation to writing the entries to that table.

FLASH Erase register only supports 2-Byte read and

write commands, starting at address 0x2E. For a

FLASH page erase to execute properly, the FLASH

write/erase enable bit in RST register (address 0x10)

must be enabled.

When writing to F_ERASE for initiation of a FLASH

table erase operation, the F_ERASE_L must contain

the value 0x55 and the F_ERASE_H must match the

value in the FLASH Table Number register (address

0x2D). This is done to greatly reduce the probability of

erroneous erase operations.

Immediately after the completion of the write opera-

tion, the SFP101 will erase the table specified by the

F_ERASE_H. During the erase, the Host must wait

over 50 ms before issuing any communications to the

SFP101.


Sendyne SFP101EVB

On Read from this register, the number of the last

table erased (0x00 - 0x03) will be returned in

the F_ERASE_H for verification (return value for

F_ERASE_L is always 0x55); by default, if no

table was erased, this register contains 0xFF55.

F_ERASE: FLASH Erase Register

Address Name Register Descrip.0x2E F_ERASE_L Bits [7:0] Protection

from accidental

erasure;

On Writes, these bits

must be 0x55, or

the Erase will not be

executed;

On Reads, these bits

will always be 0x55

0x1F F_ERASE_L Table Number for

Erase operation, 0

to 3,

any other value will

prevent execution of

the Erase command

Current Measurement RegistersThe following registers relate to the SFP101 current

measurement functions.

CUR_S: ADC Current Status (Address 0x30)

Bit Bit Symbol R/W Bit Description[7:6] CUR_ID R 01 (Current ADC

ID)

[5] Reserved

[4] D_RPT R 1:Data read was

repeated

0: New data

[3] ACC_OVR R 1: coulomb counter

overflow

0: No overflow

[2:1] Reserved

[0] COM_ER R 1: Communication

Error


Sendyne SFP101EVB

ADC Current Calibration for Zero OffsetThe SFP101 performs zero-offset calibration on the

current channel without disrupting data accumula-

tion. It does this automatically when the AUTO_CAL

bit is set in the CUR_C register (default state). How-

ever, clearing it allows the host to exercise the IC, and

to activate calibration manually by setting FORC_CAL

bit; this is utilized in factory testing only, and has no

utility for the user.

In normal operations, it is possible to set FORC_CAL

while the automatic calibration is enabled, however

this is not recommended since accuracy may suffer.

CUR_C: ADC Current Control (Address 0x31)

Bit Bit Symbol R/W Bit Description[7] Reserved

[6] AUTO_CAL R/W 0: automatic cali-

bration disabled

1: enabled (default)

[5:3] Reserved

[2] FORC_CAL W Writing 1 forces

calibration

[1] C_ACC W Writing 1 clears the

coulomb counter

registers

[0] Reserved

CUR_OUT: Current Measurement Data Output RegistersThe voltage drop across a shunt resistor is measured

by the two current ADC channels that are averaged

together (in counts). See Current Measurements with

the SFP101 section for the complete functionality.

CUR_OUT:24-bit Conversion Data (2’s complement)

Address Name Register Description0x32 CUR_OUTL ADC Data [7:0]

0x33 CUR_OUTM ADC Data [15:8]

0x34 CUR_OUTH ADC Data [23:16]

CUR_ACC: Coulomb Counting Data AccumulatorThese 8 registers are Read/Write. Either the lowest

6 bytes (0x35 – 0x3A) or the highest 6 bytes (0x37 –

0x3C) can be read in one transaction. Writes may be

issued to any registers in the set and are stored in an 8

byte buffer. When the last byte (0x3A) is written, the

multi-byte register will be updated with the value in

the buffer. The registers do not reset when data is read

from them. When the coulomb count values reach

0xC000000000000000 or 0x3FFFFFFFFFFFFFFF, the

coulomb counting overflow condition (ACC_OVR) will

be set in the CUR_CS register. Setting the C_ACC bit

of CUR_C will clear the ACC_OVR bit and reset the

coulomb count to zero. The SFP101 will keep accumu-

lating data if the register overflows.

The coulomb accumulator works by continuously add-

ing current ADC samples to the CUR_ACC register.

The coulomb count (in counts) is obtained by dividing

the value in the CUR_ACC register by the sampling

rate of the SFP101.

CUR_ACC: 64-bit Accumulated

Current Data (2’s complement)

Address Name Register Description0x35 CUR_ACC0 ACC Data [7:0]

0x36 CUR_ACC1 ACC Data [15:8]




0x3A CUR_ACC5 ACC Data [47:40]

0x3B CUR_ACC6 ACC Data [55:48]

0x3C CUR_ACC7 ACC Data [63:56]

SHNT_CAL: Shunt Calibration DataThese registers are saved in non-volatile memory

and are used to store shunt resistance calibration

data. When this register is written to, the IC will stop

all functions for 40 ms in order to write to the flash

memory.


Sendyne SFP101EVB

SHNT_CAL: 16-bit Shunt Scaling Data

Address Name Register Description0x41 SHNT_CALL Calibration Data [7:0]

0x42 SHNT_CALH Calibration Data [15:8]

CUR_GAIN: Current Gain ControlEncoded setting of the Programmable Gain Amplifier

(PGA) in the Current Measurement Section.

Effectively, this control register defines the maximum

full-scale input voltage of the shunt’s voltage drop

amplifier that will be digitized and reported without

clipping or distortion. This register is saved in non-

volatile memory.

CUR_GAIN: Setting of PGA for current sensing

(Address 0x43)

Bit Symbol R/W Bit Description[7:3] Reserved

[2:0] CUR_PGA R/W PGA settings:

[010] = FS voltage of

±300 mV


±150 mV


±75 mV


±37.5 mV


±18.75 mV

All other states of bits

[2:0] are reserved

One specific value of the whole CUR_GAIN register,

0xFF, also signifies the ±37.5 mV setting of the PGA;

this is a default value for the IC as shipped from

the factory. Thus, with the particular shunt (and its

resistance), utilized on the module, the ISH-COUNT (and

CSH-COUNT) parameters are initialized to the specific

values shown in the Electrical Specifications Table,

and corresponding to the Full-scale voltage of ±37.5

mV for the PGA. Likewise, this specific setting of the

PGA and thermal behavior of the shunt defines the

information presented for the parameter ISH-PK.

COMP_CTRL: Compensation ControlThis register provides control bits for disabling or

enabling automatic utilization of the shunt’s

Scaling (single-temperature Calibration) Data and the

shunt’s Resistance Temperature Dependence

Table (RTDT). This register is saved in non-volatile

memory.

COMP_CTRL: Control of shunt scaling and temper-

ature compensation (Address 0x44)


[4] SHNT_

COMP_DIS

R/W 1: Automatic use of

RTDT is disabled

0: Automatic use of

RTDT is enabled

Factory supplied ICs

have this bit =1

[3:1] Reserved

[0] SHNT_CAL

_DIS


SHNT_CAL is dis-

abled

0: Automatic use of

SHNT_CAL is enabled


have this bit =1


Sendyne SFP101EVB

C_TRESH: Charge Threshold ValueThis value is used for controlling operations of unidi-

rectional charge accumulators DIS_ACC and

CHARGE_ACC; specifically, when the current mea-

surement exceeds the C_TRESH, the accumulation

of the charge value will be directed to the register

CHARGE_ACC. In typical use, C_TRESH is initialized

to a small positive value. These registers are saved in

non-volatile memory.

C_TRESH: 24-bit Charge Threshold Value

(signed, 2’s complement)

Address Name Register Descrip.0x45 C_TRESH_L C_TRESH [7:0]

0x46 C_TRESH_M C_TRESH [15:8]

0x47 C_TRESH_H C_TRESH [23:16]

D_TRESH: Discharge Threshold ValueThis value is used for controlling operations of unidi-

rectional charge accumulators DIS_ACC and

CHARGE_ACC; specifically, when the current level

goes below the D_TRESH the accumulation

of the charge value will be directed to the register

DIS_ACC. In typical use, D_TRESH is initialized to a

small negative value. These registers are saved in non-

volatile memory.

D_TRESH: 24-bit Charge Threshold Value


Address Name Register Descrip.0x48 D_TRESH_L D_TRESH [7:0]

0x49 D_TRESH_M D_TRESH [15:8]

0x4A D_TRESH_H D_TRESH [23:16]

Voltage Measurement RegistersThe following registers relate to the SFP101 voltage

measurement functions.

VOLT_S: ADC Voltage Status (Address 0x50)

Bit Symbol R/W Bit Description[7:6] VOLT_ID R 10 (Volt ADC ID)

[5:4] Reserved

[3] D_RPT R 1:Data read was

repeated

0: New data

[2:1] Reserved


Error

0: No Error

VOLT_C: ADC Voltage Control (Address 0x51)


VOLT_OUT: Voltage Measurement Data Output RegistersThe voltage measured by the voltage ADC (in counts).

VOLT_OUT:24-bit Conversion Data


Address Name Register Description0x52 VOLT_OUTL ADC Data [7:0]

0x53 VOLT_OUTM ADC Data [15:8]

0x54 VOLT_OUTH ADC Data [23:16]


Sendyne SFP101EVB

VOLT_CAL: Voltage Calibration DataThese registers provide room-temperature calibration

data of the voltage measurement channel.

These registers are saved in non-volatile memory.

VOLT_CAL: 16-bit Voltage Calibration Value


Address Name Register Description0x55 VOLT_CALL VOLT_CAL [7:0]

0x56 VOLT_CALH VOLT_CAL [15:8]

VOLT_GCC: Gain & Calibration ControlThese registers provide control bit for disabling or

enabling automatic utilization of the voltage

measurement channel’s room-temperature calibra-

tion data. These registers are saved in non-volatile

memory.

VOLT_GCCL: Gain & Calibration Control for

voltage measurement channel (Address 0x57)


VOLT_GCCH: Gain & Calibration Control for volt-

age measurement channel (Address 0x58)


[0] VOLT_CAL

_DIS


VOLT_CAL is dis-

abled

0: Automatic use of

VOLT_CAL is enabled


have this bit =1

Temperature Measurement RegistersThe following registers relate to the SFP101 external

temperature measurement functions. The tempera-

ture readings are available as Y values. These registers

work with a specific thermistor circuit. See Tempera-

ture Measurements with the SFP101 section for a

detailed description of the thermistor operation.

TEMP_S: ADC Temperature Status (Address 0x70)

Bit Symbol R/W Bit Description[7:6] TEMP_ID R 11 (Temp ADC ID)

[5:4] Reserved

[3] Reserved

[2:1] Reserved


Error

TEMP_C: ADC Temperature Control (Address 0x71)



Sendyne SFP101EVB

TEMP0_R_OUT: Remote Temperature Measurement RegistersY value of the external thermistor. This value is a ratio

of the external thermistor in parallel with its reference

resistor to the reference resistor. Its values range from

0 to 16777215 (or 224 -1) and represent a range from

0 to 1.

TEMP0_R_OUT:

24-bit Temperature Conversion Data (Unipolar)

Address Name Register Description

0x72 TEMP0_R_OUTL ADC Data [7:0]

0x73 TEMP0_R_OUTM ADC Data [15:8]

0x74 TEMP0_R_OUTH ADC Data [23:16]

TEMP1_OB_OUT: Onboard Thermistor 1 RegistersY value of the first onboard thermistor. This value is a

ratio of the on-board thermistor 1 in parallel with the

reference resistor to the reference resistor. Its values

range from 0 to 16777215 (or 224 -1) and represent a

range from 0 to 1.

TEMP1_OB_OUT: 24-bit Temperature Conversion

Data (Unipolar)


0x90 TEMP1_OB_OUTL ADC Data [7:0]

0x91 TEMP1_OB_OUTM ADC Data [15:8]

0x92 TEMP1_OB_OUTH ADC Data [23:16]

TEMP2_OB_OUT: Onboard Thermistor 2 RegistersThis is the Y value of the second onboard thermistor.

This value is a ratio of the on-board thermistor 2 in

parallel with the reference resistor to the reference

resistor. Its values range from 0 to 16777215

(or 224 -1) and represent a range from 0 to 1.

TEMP2Y_OB_OUT:






TEMP3_OB_OUT: Onboard Thermistor 3 RegistersThis is the Y value of the third onboard thermistor.

This value is a ratio of the on-board thermistor 3 in

parallel with reference resistor to the reference resis-

tor. Its values range from 0 to 16777215

(or 224 -1) and represent a range from 0 to 1.

TEMP3_OB_OUT:







Sendyne SFP101EVB

TEMP0_R_C: Remote Sensor Celsius DataInternally calculated temperature of the external

thermistor expressed in degrees Celsius. This

value ranges from 0x000000 to 0xFFFFFF and rep-

resents a range from -256 °C to +256 °C. To calculate

the actual temperature, divide the signed integer value

by 215.

TEMP0_R_C:

24-bit Temperature Conversion Data (signed, 2’s

complement)


0x99 TEMP0_R_CL lsb = 30.518 μ°C

0x9A TEMP0_R_CM msb = 1 °C

0x9B TEMP0_R_CH lsb = 2 °C

TEMP1_OB_C: Onboard Thermistor 1 Celsius DataInternally calculated temperature of the first onboard

thermistor expressed in degrees Celsius.

This value ranges from 0x000000 to 0xFFFFFF and

represents a range from -256 °C to +256 °C. To calcu-

late the actual temperature, divide the signed integer

value by 215.

TEMP1_OB_C:

24-bit Celsius Temperature Value (signed, 2’s

complement)


0x9C TEMP1_OB_CL lsb = 30.518 μ°C

0x9D TEMP1_OB_CM msb = 1 °C

0x9E TEMP1_OB_CH lsb = 2 °C

TEMP2_OB_C: Onboard Thermistor 2 Celsius DataInternally calculated temperature of the second on-

board thermistor expressed in degrees Celsius.




value by 215.

TEMP2_OB_C:


complement)


0x9F TEMP2_OB_CL lsb = 30.518 μ°C

0xA0 TEMP2_OB_CM msb = 1 °C

0xA1 TEMP2_OB_CH lsb = 2 °C

TEMP3_OB_C: Onboard Thermistor 3 Celsius DataInternally calculated temperature of the second on-

board thermistor expressed in degrees Celsius.




value by 215.

TEMP3_OB_C:


complement)


0xA2 TEMP3_OB_CL lsb = 30.518 μ°C

0xA3 TEMP3_OB_CM msb = 1 °C

0xA4 TEMP3_OB_CH lsb = 2 °C


Sendyne SFP101EVB

Accumulated Charge and Discharge Data

CHARGE_ACC: 64-bit Accumulated Charge ValueAccumulator (coulomb counter) for charging (posi-

tive) currents. In typical operations these registers will

contain an increasing positive value.

CHARGE_ACC: 64-bit Accumulated Charge Value


Address Name Register Description0xC0 CHARGE_

ACC0

Charge Data [7:0]

0xC1 CHARGE_

ACC1

Charge Data [15:8]

0xC2 CHARGE_

ACC2

Charge Data [23:16]

0xC3 CHARGE_

ACC3

Charge Data [31:24]

0xC4 CHARGE_

ACC4

Charge Data [39:32]

0xC5 CHARGE_

ACC5

Charge Data [47:40]

0xC6 CHARGE_

ACC6

Charge Data [55:48]

0xC7 CHARGE_

ACC7

Charge Data [63:56]

DIS_ACC: 64-bit Accumulated Discharge ValueAccumulator (coulomb counter) for discharging

(negative) currents. In typical operations these

registers will contain a decreasing negative value.

CHARGE_ACC: 64-bit Accumulated Discharge

Value (signed, 2’s complement)

Address Name Register Description0xC8 DIS_ACC0 Discharge Data [7:0]

0xC9 DIS_ACC1 Discharge Data [15:8]

0xCA DIS_ACC2 Discharge Data [23:16]

0xCB DIS_ACC3 Discharge Data [31:24]

0xCC DIS_ACC4 Discharge Data [39:32]

0xCD DIS_ACC5 Discharge Data [47:40]

0xCE DIS_ACC6 Discharge Data [55:48]

0xCF DIS_ACC7 Discharge Data [63:56]


Sendyne SFP101EVB

Software Features and Operations

Sendyne’s control software for the SFP101EVB

initializes the SFP101 IC for the desired communica-

tions rate (9.6 kBd, 19.2 kBd - default, or 115.2 kBd),

and polls for data at the selected acquisition rate; it

receives the data, checks the data for communications

errors, and decodes the values for voltage, current,

coulomb counts (three independent values for Total,

Charge, and Discharge accumulators), and tempera-

tures for one external and three on-board thermis-

tors. All of these nine channels can be sampled at the

acquisition rates up to 20 Hz, when the fastest com-

munications rate of 115.2 kBd is selected. All SFP101

IC registers can be observed and Read/Write registers

can be manipulated using this software.

Figure 24: SFP101SFT MAIN SCREEN


Sendyne SFP101EVB

The software presents the real-time data from seven

channels in a digital panel meter format. In addition,

a separate window can be opened (by clicking the ±C

button) to display Charge and Discharge accumula-

tors, also in the digital panel meter format.

Independent real-time graphs of three values, namely

the voltage, current, and temperature of the external

thermistor, can be displayed if individually enabled by

clicking on the buttons represented below.

These graphs can zoom on all axes, with available

automatic zooming on the Y axis and automatic real-

time scrolling on the X axis.

If data logging is enabled, the software saves data with

timestamps for all nine channels, for an indefinite

duration, organizing the data in sequential files of

user-selectable size (to simplify manipulations of large

amounts of data, and to minimize data loss in case of a

power outage).

Previously logged data can be replayed and observed,

for all nine of the acquired data channels. The same

zoom and pan functionality is available as for the real-

time graphs except for the automatic scrolling on the

X axis.

Logging DataThe data logging functionality provides for saving of

the data received by the SFP101 Control Software.

Logging must be enabled before starting the acquisi-

tion (before Start button is pressed), or data will not

be saved.

In order to enable logging, click on the Logging drop

down menu, then select Log File… A save file dialog

window will pop up, allowing you to name the file and

to choose the location (drive and subdirectory) where

it will be saved. Note that a timestamp will be auto-

matically appended to the file’s name. After clicking

Save in the dialog window, the status in the bottom

right of the Main window will indicate the name of the

file.

When the Start button is pressed, while logging is

enabled, all the data received by the SFP101 Control

Software will be saved.

To disable logging, click on the Logging drop down

menu, then select Log File… If logging is enabled,

there will be a check mark next to the Log File item. In

this case, clicking Log File will not bring up a menu,

but instead will remove the check mark, disabling the

logging. The status in the bottom right of the Main

screen will now say “Logging Disabled”.

In the Logging menu, the Max Points Per File option

lets one choose how many points a single log file can

hold. When the file reaches the maximum number of

points it can hold, a new log file is created with the

same name and an appropriate sequential timestamp.

The data in the new file simply reflects a continuation

of the uninterrupted data acquisition process; when

displayed by the replay action of the software, the

observed data will be seamless.

V A EXT. T

±C


Sendyne SFP101EVB

Viewing SettingsClicking on the yellow Settings button brings up an

independent Settings window. Note: This button is

only active when data is not being acquired; the FTDI

cable connected to the SFP101EVB module must

be selected (from the list in Comm/Acq-COM_Port

menu) in order to open the Settings window, since the

values displayed are acquired from the SFP101EVB at

the time instance when the Settings window is opened.

This window shows the internal registers and board

configuration of the SFP101 and allows modification

of non-read-only values. The values can be viewed or

modified in either Hex or decimal notation.

To change the value of a data register, write the data in

the textbox and click the Write button. Some registers

are nonvolatile and get saved to flash. Writing to these

registers will cause the software to reset the SFP101.

The register window also contains parameters that

interact with the SFP101 but are not SFP101 registers.

These values are saved within the software itself using

the Save button.

Viewing Previously Logged GraphsTo open previously logged graphs, click on the Graphs

drop down menu and choose Select Saved Graphs.

This will bring up the open file dialog. Choose a .txt

file which was previously recorded by the SFP101

Control Software and press Open to open the Replay

window. In the Replay window there will be a list of all

the files that share a name with the chosen file (ignor-

ing timestamp).

Select one or more of these files and a data acquisi-

tion channel you would like to see, press the Update

Graph button, and the data will appear on the graph.

Multiple instances of this window can be open, with

same or different channels of acquisition and intervals

of time.

While the real-time graphs are available only for three

data acquisition channels, the replay graphs can be

displayed for all nine channels.

Software Elements

Main ScreenThe main screen shows the instrument boxes for the

seven different measurements of the module: Voltage,

Current, Coulomb Count, main Temperature Sensor,

and three onboard “shunt” temperature sensors.

The Current box contains a graphical representation

of the current in the form of a moving bar. This bar

moves in a logarithmic-like scale proportional to the

current, and the direction of the movement denotes

the direction of the current.

Two buttons appear : Start/Stop and Settings. Start/

Stop starts and stops the acquisition of data from the

module. In order to acquire measurements, an FTDI

cable connected to the SFP101EVB must be selected

from the Comm menu, as well as the appropriate baud

rate and acquisition rate.

The Settings button opens a new window that allows

the configuration of the SFP101. An FTDI cable con-

nected to the SFP101EVB must be selected in order to

open this window.

MenusFile

Selecting the Exit option will exit the program.

Logging

The Max Samples Per File option selects the maxi-

mum amount of points a log file can contain. When

the maximum amount of points has been acquired,

a new file will be created with the same name and an

appropriate timestamp appended to it.

The Log File option opens a dialog to select the name

of the file, location where files will be saved, and en-

ables/disables logging. A timestamp will be appended

at the end of the chosen log file name. Note that log-


Sendyne SFP101EVB

ging does not save the points that were received before

it was enabled.

Comm/Acq

Selecting the COM Port option allows you to choose one

particular FTDI cable for communications. If several

FTDI cables are connected to the PC, a selection list is

presented, organized by the individual serial numbers.

The Baud Rate option selects the baud rate for commu-

nications with SFP101EVB.

The Acquisition Period option selects how often the

data is sampled from the board.

Graphs

The Max Samples Per Graph option selects the maxi-

mum amount of points the graphs can display at once.

This setting is only applicable to the real-time graphs;

the Replay graphs automatically adjust to the amount

of data selected for display. Note that a large number of

points can affect real time performance.

The Select Saved Graph option opens previous graphs

for viewing.

Help

The User Manual option shows the software section of

the SFP101EVB datasheet.

Settings WindowNote: All register data is loaded from the SFP101 when

the Settings window opens. This window can only be

opened when the board is not acquiring data.

Tabs

There are tabs for General Purpose, Current, Shunt,

Voltage, and Temperature register groupings. To dis-

play and/or modify the settings of registers on a specific

Tab, its name should be clicked.

Control Registers

Bits in these registers can be manipulated by clicking

on their individual bit buttons. All have tool tips to

show what function they correspond to. Every time a

bit button is clicked, its value is changed and sent to the

SFP101, then read back and displayed.

Data Registers

The data registers let you input a large (more than one

byte) number into a multi byte register in the SFP101.

You may switch between hex and decimal view.

Every time a number is written (by pushing the write

button), it is converted to a set of bytes and sent to the

SFP101, then read back and displayed.

Read Only Registers

These registers contain data from the IC; this data can-

not be changed.

Non-Volatile Registers

Non-volatile registers are saved in the on-board

memory that retains the values even when the power

for the module is removed or the module is reset; this

non-volatile memory is internal to the SFP101 IC. Writ-

ing to non-volatile registers will cause the software to

reset the SFP101 and thus automatically apply the new

settings.

Operating Parameters

The Settings window also contains parameters that

interact with the SFP101 but are not SFP101 registers.

These values are saved or recalled within the software

itself using the Save or Load buttons (located only on

some of the Tabs, as needed).


Sendyne SFP101EVB

Description of Settings’ TabsGeneral Purpose Tab

CommuniCations RegisteR

Bits 0 and 1 denote the baud rate. It cannot be

changed using this interface and must be selected

from the Comm menu on the main screen. For the Set-

tings menu, the baud rate will always be set to 19200,

since the baud rate selection only applies to real time

data acquisition. Bit 2 is the communications reset

function.

PoweR and Reset RegisteR

Bit 0 controls the reset function. Pressing this button

will reset the IC.

PaRt numbeR Code, manufaCtuRing Code, and VeR-sion Code RegisteRs

These values are used for manufacturing, see data-

sheet (Registers section, page 50) for more details.

PaRt numbeR stRing RegisteR

Shows the part number of the IC. This value is en-

coded as an ASCII string.

seRial numbeR RegisteR

Shows the serial number of the board. This value is

encoded as a hex number.

Figure 25: General Purpose Tab


Sendyne SFP101EVB

Current Tab

CuRRent ContRol RegisteR

Bit 1 of this register clears all three Coulomb counters,

and bit 2 forces the board to perform an offset calibra-

tion; both of these bits are non-persistent write-only

bits, the bit values will return to 0 when the requested

action is completed.

Bit 6 turns the automatic offset calibration on when

set high and off when set low, the setting of this bit is

persistent and will be maintained unless the operating

power is removed or the IC is reset; it defaults to 1 on

reset. The user should not need to manipulate bit 6, it

is used for factory testing only.

CuRRent data RegisteR

The Current Data Register shows the raw cur-

rent value in ADC counts, this is a 24-bit signed 2’s

complement number.

Coulomb Counting, ChaRge, and disChaRge data RegisteRs

These registers are shown as 8 bytes, these are 64-bit

signed 2’s complement numbers.

thReshold RegisteRs

These registers show the charge and discharge

threshold settings as raw ADC counts, these are 24-bit

signed 2’s complement numbers.

Figure 26: Current Tab


Sendyne SFP101EVB

Shunt Tab

CuRRent gain ContRol RegisteR and full sCale adC inPut setting

The full scale ADC input setting allows the use of dif-

ferent shunts with the SFP101 IC and EVB. It controls

the maximum sensing voltage the current channel’s

ADC can accept. This setting is used for shunts with

higher and lower full scale voltage output than the

default shunt. This setting should be adjusted to be

greater or equal to the shunt’s full scale output voltage

if the current being measured will use the shunt’s full

range. It can also be smaller than the shunt’s full scale

output voltage if a smaller current range is used. The

Default setting sets this and the shunt parameters to

their defaults for the SFP101EVB. Note that the ADC

gain is adjusted according to the full scale value. To

calculate the voltage value of a single ADC count, use

the equation:

VCS-ADC = VIN-CS / 223

While the ADC noise and offset specifications are dif-

ferent for each full scale ADC input setting, the total

accuracy of the system is also dependent on the shunt

and it’s connection to the board. A shunt and the

SFP101EVB should be characterized and calibrated

together as a complete system.

shunt PaRameteR adjustment

This setting allows the user to specify the parameters

of different shunts. There are two parameters for ev-

ery shunt; full scale current and full scale voltage. Full

scale current is the maximum current the shunt can

handle. Full scale voltage is the voltage the shunt will

output when the maximum current is applied. These

two values are used to calculate the shunt resistance.

The resistance value calculated with these settings can

be calibrated more precisely with the Shunt Calibra-

tion Data Register.

shunt CalibRation data RegisteR

This register holds the value of a single point cali-

bration for the current channel. It is used to finely

compensate for a shunt’s variation in resistance due to

manufacturing. The SFP101EVB comes pre calibrated

with this number. The automatic application of the

internal calibration is enabled by the Enable Internal

Shunt Calibration check box in the Compensation

Control Register field.

ComPensation ContRol RegisteR The SFP101 has several options to compensate for

inaccuracies. Using the Enable Internal Shunt Calibra-

tion checkbox will enable a single point calibration for

the shunt. The calibration parameter is specified by

the Shunt Calibration Data register. The Enable RTDT

Correction checkbox causes the SFP101 to apply

shunt temperature dependent resistance compensa-

tion, allowing further accuracy improvements. RTDT

correction operations require a table to be uploaded,

see the Shunt Thermal Compensation section of this

document for more details.

Figure 27: Shunt Tab


Sendyne SFP101EVB

Voltage Tab

Voltage ContRol RegisteR

This register is reserved for future functionality.

Voltage data RegisteR

The Voltage Data Register shows the raw voltage value

in ADC counts, this is a 24-bit signed 2’s complement

number.

exteRnal ResistanCe on Voltage inPut setting

In order to measure higher voltages, an external

resistor can be added to the voltage channel input

of the SFP101EVB. This setting allows the external

resistor to be factored into the voltage divider calcu-

lations. The resistor value is entered in kOhms, and

the software automatically calculates the new divider

ratio when it is saved. Note that any external resistors

will require calibration to achieve accurate voltage

measurements.

Voltage CalibRation data RegisteR

This register holds the value of a single point calibra-

tion for the voltage channel. This is used to finely com-

pensate for the variation in attenuation of the resistor

divider on the voltage channel input.

Voltage gain and CalibRation RegisteR

Setting the Enable Internal Voltage Calibration check-

box enables an automatic application of the single

point calibration for the voltage channel. The calibra-

tion parameter is specified by the Voltage Calibration

Data register.

Figure 28: Voltage Tab


Sendyne SFP101EVB

Temperature Tab

temPeRatuRe ContRol RegisteR

This register is reserved for future compatibility.

Remote temPeRatuRe RegisteRs

These registers show the raw values of the tempera-

ture readings for the Y and the Celsius values.

on boaRd temPeRatuRe 1/2/3 RegisteRs

These registers show the raw values of the tempera-

ture readings for the Y and the Celsius values.

Figure 29: Temperature Tab


Sendyne SFP101EVB

Graph WindowReal Time Graph Display

Graphs are updated as new data is received. When the

cursor is located in the chart area, the left mouse click

zooms in on a specific area on the Y axis, right click

zooms out on the Y axis. The Scroll wheel and Y axis

magnifying glass + and - buttons zoom in and out on

the Y axis. Axis X magnifying glass + and - buttons

zoom in and out on the X axis.

Checking the Auto Zoom check box causes the graph

to automatically zoom on the Y axis to fit the on screen

data into the window. Units radio buttons change the

numerical scale of the graph. Checking the Auto Scroll

check box causes the graph to scroll to newly added

points automatically.

Figure 30: Real-Time Measurement of Remote Voltage


Sendyne SFP101EVB

Replay Graph WindowMenu “Graphs/Select Saved Graph…” opens a window

that lets you select a file to view. The file must be a

log file from the SFP101. Opening a file puts all files

with that name (ignoring timestamps appended to the

name) into the replay window.

The Sensor drop down menu lets you choose which

sensor will be shown on the graph. One can pick any

sensor which was logged by the SFP101.

The menu area on the bottom-left of the Replay Win-

dow contains a list of individual files that correspond

to the chosen name. One or more of these files can be

selected and shown on the graph. Data from multiple

files are seamlessly concatenated onto one graph.

The Update Graph button displays the chosen files

on the graph. The data will be scaled according to the

units’ radio buttons. The Click to Zoom radio buttons

determine which axis is zoomed when the graph is

clicked. Left click zooms in, right click zooms out. All

other zoom controls work as described in the Graph

Window section.

Figure 31: Replay Measurement of Remote Voltage


Sendyne SFP101EVB

Mechanical Drawing


Sendyne SFP101EVB

Schematics, Page 1

Date:

August 14, 2014Sheet

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BSFP101.sch

Title

SFP101EVB Module - TOP sheet

212-966-0600

New York, NY 10013

250 West Broadway

(c)2014 SENDYNE Corp

L1

FBEAD

1

2

3

4

5678U4

IXDI604SIA

C3

10uF

1

2

3

45U3

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C5

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C0G

1234 5

6

7

8

L2

GT03_111_069_C

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C1

10uF

C2

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1

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2

VIN

3

U1

MCP1703CB

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C6

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10

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Isolated DC/DC Converter,

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SFP101_2.SCHCH1P

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TH2SW

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AFE/CONTROLLER SFP101

SFP101_3.SCH

CH1P

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CH1SW

CH2SW

AFETXD

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THER_P

THER_N

VX1REF

VX1DIV

EXT_NACT

EXT_TH_N

EXT_TH_P

ISOAVDD

ISOFHV

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Power Conditioning and Filtering

R5

10k

ISOFHV

ISOFHV

C10 10uF GND

GND

GND

C7 100nF

nCTS

VCC

TxD

RxD

nRTS

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1

2

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4

5

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Digital Isolator

1

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Level Shifters

CH2SW

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CH2P

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TH2SW

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THER_N

EXTERNAL VOLTAGE SENSE

AND EXTERNAL THERMISTOR

ISOVSS

ISOGND

ISOGND

EXT_VX

EXTTHP

EXTTHN

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ISOGND

ISOVSS

ISOVSS

Miniature screw

terminals block.

1 2 3 4

J3

R9

4.990k1206

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R10

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1%R7

4.990k1206

0.1%

R11

1.0k1206

1%

ISOAVDD

1.0


Sendyne SFP101EVB

Schematics, Page 2

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Title

SFP101EVB Module - Analog Conditioning

212-966-0600

New York, NY 10013

250 West Broadway


C26

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1

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C16

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ISOVSS

CH2 Driver

12

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ISOFHV

ISOVSS

1.0


Sendyne SFP101EVB

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Title

SFP101EVB Module - AFE/Controller SFP101

212-966-0600

New York, NY 10013

250 West Broadway


AFETXD

AFERXD

AFERXD

AFETXD

TP7

TP8

R22

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R23

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R24

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R25

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Shunt signal switching control

ISOGND

and calibration mode activation

CH1P

CH1N

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KEEP SHORT!!!

antialiasing filters

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RIO4

46

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47

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C19

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Factory use ONLY.

Factory Test and spare pins

that require pull-up resistors.

C17

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ISOVDD

ISOVSS

ISOVSS

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TH1SW

TH2SW

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C25

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C20

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C23

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EXT_TH_P

EXT_TH_N

EXT_NACT

EXT_NACT

EXT_TH_N

EXT_TH_P

ISOVSS

ISOVSS

12

34

56

78

91 0J6

HEADER2X5

Factory use ONLY.

Factory Test and

spare pins.

ISOVSS

ISOFHV

ISOFHV

ISOFHV

ISOVSS

RIO1

RIO2

1.0


Sendyne SFP101EVB

Ordering

Available devices

Model Temperature Range

Description Package Ordering Quantity

SFP101EVB –40 °C to +125 °C Module NA 1

SFP101EVB-KIT –40 °C to +85 °C Module, Cable, Software NA 1

SFP100CBL –40 °C to +85 °C Module cable NA 1

SFP101SFT NA Module software NA 1

Ordering InformationSFP101EVB

SFP101 — Sendyne base part number

EVB — Module


Sendyne SFP101EVB

Revision History

Revision Table

Revision Number Date Comments

1.0 09/09/2014 Preliminary; initial release

Information contained in this publication regarding

device applications and the like is provided only for

your convenience and may be superseded by updates.

It is your responsibility to ensure that your application

meets with your specifications.

SENDYNE MAKES NO REPRESENTATIONS OR

WARRANTIES OF ANY KIND WHETHER EX-

PRESSED OR IMPLIED, WRITTEN OR ORAL,

STATUTORY OR OTHERWISE, RELATED TO THE

INFORMATION, INCLUDING BUT NOT LIMITED

TO ITS CONDITION, QUALITY, PERFORMANCE,

MERCHANTABILITY OR FITNESS FOR PURPOSE.

Sendyne disclaims all liability arising from this in-

formation and its use. Use of Sendyne devices in life

support and/or safety applications is entirely at the

buyer’s risk, and the buyer agrees to defend, indemni-

fy and hold harmless Sendyne from any and all dam-

ages, claims, suits, or expenses resulting from such

use. No licenses are conveyed, implicitly or otherwise,

under any Sendyne intellectual property rights.

PatentsUS Pat. 8,264,216

US Pat. 8,289,030

Other patents pending

TrademarksThe Sendyne name and logo are registered trademarks

of Sendyne Corp.

All other trademarks mentioned herein are properties

of their respective owners.

© 2014 Sendyne Corp.

All Rights Reserved.

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Sendyne SFP101EVB Datasheet V1

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Transcript of Sendyne SFP101EVB Datasheet V1