8/8/2019 LTC3105 Datasheet
1/16
LTC3105
1
3105p
TYPICAL APPLICATION
FEATURES DESCRIPTION
400mA Step-Up DC/DCConverter with Maximum Power
Point Control and 250mV Start-Up
The LTC3105 is a high efficiency step-up DC/DC converterthat can operate from input voltages as low as 200mV. A250mV start-up capability and integrated maximum powerpoint controller (MPPC) enable operation directly from lowvoltage, high impedance alternative power sources such asphotovoltaic cells, TEGs (thermoelectric generators) andfuel cells. A user programmable MPPC set point maximizesthe energy that can be extracted from any power source.Burst Mode operation, with a proprietary self adjustingpeak current, optimizes converter efficiency and outputvoltage ripple over all operating conditions.
The AUX powered 6mA LDO provides a regulated rail forexternal microcontrollers and sensors while the mainoutput is charging. In shutdown, IQ is reduced to 4Aand integrated thermal shutdown offers protection fromovertemperature faults. The LTC3105 is offered in 10-lead3mm 3mm 0.75mm DFN and 12-lead MSOP packages.
Output Current vs Input Voltage
APPLICATIONS
n Low Start-Up Voltage: 250mVn Maximum Power Point Controln Wide VIN Range: 0.2V to 5Vn Auxiliary 6mA LDO Regulatorn Burst Mode Operation: IQ = 22An Output Disconnect and Inrush Current Limitingn VIN > VOUT Operationn Antiringing Controln Soft Startn Automatic Power Adjustn Power Good Indicatorn 10-Lead 3mm 3mm 0.75mm DFN and 12-Lead
MSOP Packages
n Solar Powered Battery/Supercapacitor Chargersn Energy Harvestingn Remote Industrial Sensorsn Low Power Wireless Transmittersn
Cell Phone, MP3, PMP and GPS Accessory Chargers
L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are r egistered trademarksand ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are theproperty of their respective owners.
3105 TA01a
10F
Li-Ion4.2V
1020k
0.2V TO 5V
VOUT4.1V
332k
FB
PGOOD
LDO
FBLDO
MPPC
VIN
SHDN
AUX
SW
VOUT
4.7F
2.2V
40.2k
1F
LTC3105
GND
10F
10H
PHOTOVOLTAICCELL
ONOFF
+
Single Photovoltaic Cell Li-Ion Trickle Charger
INPUT VOLTAGE (V)
0.20
OUTPUTCURRENT(mA)
20
40
60
0.3 0.4 0.5 0.6 0.80.7 0.9
80
10
30
50
70
1.0
3105 TA01b
VOUT = 5V
VOUT = 3.3V
VOUT = 4.2V
MPPC DISABLED
Electrical Specifications Subject to Change
8/8/2019 LTC3105 Datasheet
2/16
LTC3105
2
3105p
ABSOLUTE MAXIMUM RATINGS
SW VoltageDC ............................................................ 0.3V to 6VPulsed (
8/8/2019 LTC3105 Datasheet
3/16
LTC3105
3
3105p
ELECTRICAL CHARACTERISTICS
Note 1: Stresses beyond those listed under Absolute Maximum Ratingsmay cause permanent damage to the device. Exposure to any AbsoluteMaximum Rating condition for extended periods may affect devicereliability and lifetime.
Note 2: The LTC3105 is guaranteed to meet performance specifications
from 0C to 85C. Specifications over the 40C to 85C operatingtemperature range are ensured by design, characterization and correlationwith statistical process controls.
The l denotes the specifications which apply over the full operatingtemperature range, otherwise specifications are at TJ = 25C. VAUX = VOUT = 3.3V, VLDO = 2.2V, VIN = 0.6V, unless otherwise noted.
PARAMETER CONDITIONS MIN TYP MAX UNITS
Step-Up Converter
Input Voltage l 5 VInput Start-Up Voltage
TA = 0C to 85Cl 0.25 0.4
0.36VV
Output Voltage Adjust Range l 1.5 5.25 V
Feedback Voltage (FB Pin) l 0.988 1.008 1.028 V
VOUT IQ in Operation VFB = 1.10V 22 A
VOUT IQ in Shutdown SHDN = 0V 6 A
VIN Current in Shutdown VSHDN = VOUT = VAUX = 0V 4 A
MPPC Pin Output Current VMPPC = 0.6V 9.72 10 10.28 A
SHDN Input Logic High Voltage VOUT > 1.4V l 1.1 V
SHDN Input Logic Low Voltage VOUT > 1.4V l 0.3 V
N-Channel SW Pin Leakage Current VIN = VSW = 5V, VSHDN = 0V 1 10 A
P-Channel SW Pin Leakage Current VIN = VSW = 0V, VOUT = VAUX = 5.25V 1 10 A
N-Channel On-Resistance: SW to GND 0.5
P-Channel On-Resistance: SW to VOUT 0.5
Peak Input Current Limit VFB = 0.90V, VMPPC = 0.4V (Note 3) 0.4 0.45 A
Valley Current Limit VFB = 0.90V, VMPPC = 0.4V (Note 3) 0.3 0.35 A
PGOOD Threshold (% of Feedback Voltage) VOUT Falling 85 90 95 %
LDO Regulator
LDO Output Voltage External Resistive Divider, VOUT = 5.25VVFBLDO = 0V
l
l
1.42.16
2.2
52.24
VV
Feedback Voltage (FBLDO Pin) Using External Resistive Divider l 0.988 1.008 1.028 VLoad Regulation ILDO = 1mA to 6mA 0.40 %
Line Regulation VAUX = 2.5V to 5V 0.15 %
Dropout Voltage ILDO = 6mA, VOUT = VAUX = 2.2V 78 mV
LDO Current Limit VLDO 0.5V Below Regulation Voltage l 6 12 mA
LDO Reverse-Blocking Leakage Current VIN = VAUX = VOUT = 0V, VSHDN = 0V 1 A
Note 3: Current measurements are performed when the LTC3105 is notswitching. The current limit values measured in operation will be somewhathigher due to the propagation delay of the comparators.
Note 4: This IC includes over temperature protection that is intendedto protect the device during momentary overload conditions. Junction
temperature will exceed 125C when overtemperature protection is active.Continuous operation above the specified maximum operating junctiontemperature may impair device reliability
8/8/2019 LTC3105 Datasheet
4/16
LTC3105
4
3105p
VOUT Reverse IQ vs TemperatureDuring Shutdown
VOUT Reverse IQ vs TemperatureDuring Input UVLO
UVLO Threshold vs TemperatureMPPC Current Variationvs Temperature
LDO Soft-Start Durationvs LDO Load
Minimum Input Start-Up Voltagevs Temperature
Shutdown Thresholdsvs Input Voltage IC Enable Delay vs Input Voltage
TYPICAL PERFORMANCE CHARACTERISTICS TA = 25C, VAUX = VOUT = 3.3V, VLDO = 2.2V,VIN = 0.6V, unless otherwise noted.
TEMPERATURE (C)
45
INPUTVOLTAGE(mV)
280
15 15 45
240
260
340
220
200
320
300
30 0 75 9030 60
3105 G01
TEMPERATURE (C)
45
CHANGEFROM2
5C(%)
5
20
25
15 15 45
15
10
10
15
20
25
5
0
30 0 75 9030 60
3105 G04TEMPERATURE (C)
45
CHANGEFROM2
5C(%)
0.5
15 15 45
0.5
2.0
0
2.5
1.0
1.5
1.5
1.0
30 0 75 9030 60
3105 G05LDO LOAD CURRENT (mA)
11.20
SOFT-S
TARTTIME(ms)
1.30
1.40
2 3 4 5
1.50
1.25
1.35
1.45
6
3105 G06
TEMPERATURE (C)
45
IQ(
A)
8
18
15 15 45
4
14
6
16
2
0
12
10
30 0 75 9030 60
3105 G07
SHDN = 0V
TEMPERATURE (C)
45
IQ(
A)
8
15 15 45
4
14
6
16
2
0
12
10
30 0 75 9030 60
3105 G08
VIN = 0V
SUPPLY VOLTAGE, VIN OR VAUX (V)
00
THRESHOLDVOLTAGE(mV)
200
400
600
1 2 3 4
800
1000
100
300
500
700
900
5
3105 G02
IC DISABLE
IC ENABLE
DELAYTIME(s)
1000
3105 G03
10
100
1 54320
SUPPLY VOLTAGE, VIN OR VAUX (V)
OUTPUT VOLTAGE (V)
1.50
MAXIMUMI
NPUTVO
LTAGE(V)
1.0
2.0
3.0
2.0 3.0 4.02.5 3.5 4.5 5.0
4.0
5.0
0.5
1.5
2.5
3.5
4.5
5.5
3105 G09
NONSYNCHRONOUSOPERATION
SYNCHRONOUSOPERATION
VIN to Ensure SynchronousOperation
8/8/2019 LTC3105 Datasheet
5/16
LTC3105
5
3105p
Exiting MPPC Control onInput Voltage Step
IPEAK and IVALLEY Changevs Temperature
Input and Output Burst RippleEfficiency vs Output Current andPower Loss, VOUT = 3.3V
Efficiency vs Output Current andPower Loss, VOUT = 5V
No-Load Input Currentvs Input Voltage
TYPICAL PERFORMANCE CHARACTERISTICS TA = 25C, VAUX = VOUT = 3.3V, VLDO = 2.2V,VIN = 0.6V, unless otherwise noted.
INPUT VOLTAGE (V)
0.20
INPUT
CURRENT
(A)
200
400
600
0.4 0.6 0.8 1.0
800
100
300
500
700
1.2
3105 G16
VOUT = 3.3V
OUTPUT CURRENT (mA)
0.01
EFFICIENCY(%)
POWERLOSS(mW)
60
70
80
50
40
10.1 10 100
10
0
30
90
20
10
0.1
100
1
3105 G14
VIN = 0.6VVIN = 0.8VVIN = 1V
EFFICIENCY
POWER LOSS
OUTPUT CURRENT (mA)
0.01
EFFICIENCY(%)
POW
ERLOSS(mW)
60
70
80
50
40
10.1 10 100
30
100
90
20
100
0.1
1000
10
1
3105 G15
VIN = 3VVIN = 2VVIN = 1.5V
EFFICIENCY
POWER LOSS
TEMPERATURE (C)
45
CHANGEFROM2
5C(%)
0.5
15 15 45
1.5
1.0
1.0
2.0
2.5
0.5
0
30 0 75 9030 60
3105 G11
IVALLEY
IPEAK
TIME (s)
0 15 30 45 60 75
3105 G10
VIN VOLTAGE200mV/DIV
INDUCTORCURRENT100mA/DIV
MPPC VOLTAGE200mV/DIV
VMPPC = 400mV
INPUT VOLTAGE (V)
0.2540
EFFICIENCY(%)
60
80
1.25 2.25 3.25 4.25
100
50
70
90
5.25
3105 G12
VOUT = 3VILOAD = 10mALDO = 2.2V
TIME (s)
0 50 100 150 200 250 300
3105 G13
OUTPUTVOLTAGE
50mV/DIV
INPUTVOLTAGE5mV/DIV
SW CURRENT200mA/DIV
VIN = 0.6VCIN = 470F
VOUT = 3.3VIOUT = 15mACOUT = 10F
Efficiency vs VIN
8/8/2019 LTC3105 Datasheet
6/16
LTC3105
6
3105p
PIN FUNCTIONS
FB (Pin 1/Pin 1): Step-Up Converter Feedback Input. Con-nect the VOUT resistor divider tap to this input. The outputvoltage can be adjusted between 1.5V and 5.25V.
LDO (Pin 2/Pin 2): LDO Regulator Output. Connect a 4.7For larger capacitor between LDO and GND.
FBLDO (Pin 3/Pin 3): LDO Feedback Input. Connect theLDO resistive divider tab to this input. Alternatively, con-necting FBLDO directly to GND will configure the LDOoutput voltage to be internally set at 2.2V (nominal).
SHDN (Pin 4/Pin 4): Logic Controlled Shutdown Input.With SHDN open, the converter is enabled by an internal2M pull-up resistor. The threshold voltage for this pin
adjusts based on the input and output voltages to allowshutdown at all voltages. See the curves in the TypicalPerformance Characteristics section of this data sheetfor details.
SHDN = Low: IC Disabled
SHDN = High: IC Enabled
MPPC (Pin 5/Pin 5): Set Point Input for MaximumPower Point Control. Connect a resistor from MPPC toGND to program the activation point for the MPPC loop.To disable the MPPC circuit, connect MPPC directly
to GND.VIN (Pin 6/Pin 8): Input Supply. Connect a decouplingcapacitor between this pin and GND. The PCB trace lengthfrom the VIN pin to the decoupling capacitor should be asshort and wide as possible. When used with high imped-ance sources such as photovoltaic cells, this pin shouldhave a 10F or larger decoupling capacitor.
GND (Exposed Pad Pin 11/Pins 6, 7) : Small Signal andPower Ground for the IC. The GND connections should besoldered to the PCB ground using the lowest impedance
path possible.
SW (Pin 7/Pin 9): Switch Pin. Connect an inductor betweenSW and VIN. PCB trace lengths should be as short as pos-sible to reduce EMI. While the converter is sleeping or isin shutdown, the internal antiringing switch connects theSW pin to the VIN pin in order to minimize EMI.
PGOOD (Pin 8/Pin 10): Power Good Indicator. This is anopen-drain output. The pull-down is disabled when VOUThas achieved the voltage defined by the feedback divideron the FB pin. The pull-down is also disabled while the IC
is in shutdown mode.
VOUT (Pin 9/Pin 11): Step-Up Converter Output. This is thedrain connection of the main output internal synchronousrectifier. A 10F or larger capacitor must be connectedbetween this pin and GND. The PCB trace length from theVOUT pin to the output filter capacitor should be as shortand wide as possible.
AUX (Pin 10/Pin 12): Auxiliary Voltage. Connect a 1Fcapacitor between this pin and GND. This pin is used bythe start-up circuitry to generate a voltage rail to power
internal circuitry until the main output reaches regulation.AUX and VOUTare internally connected together once VOUTexceeds VAUX.
(DFN/MSOP)
8/8/2019 LTC3105 Datasheet
7/16
LTC3105
7
3105p
2MSHDN FBLDO
1.5V TO5.25V
VOUT
AUX
LDO
CIN10F
RMPPC
90mV
L1
10H
Exposed Pad
INPUT UVLO
USER SHUTDOWN
SHUTDOWN
VALLEY CURRENT LIMIT
PEAK CURRENTLIMIT
VIN6
4
7
11
9
+
LOGIC
+
+
SLEEPR3
R4
SHUTDOWN
CLDO4.7F
1.008V
1.008V
SLEEPSHUTDOWN
VIN
VCC
VAUX
++
+
VIN
10AMPPC
SW
5
LOW VOLTAGESTART-UP CURRENT
ADJUST
BURSTCONTROL
0.2VTO 5V
+
3
PGOOD
FB1
10
2
R1
R2
COUT10F
CAUX1F
0.9V
FB
8
3105 BD
SHORTCONTROL
WELLCONTROL
OR
VCC
SLEEP
VCCVAUX
VIN
gm
+
BLOCK DIAGRAM (Pin Numbers for DFN Package Only)
8/8/2019 LTC3105 Datasheet
8/16
LTC3105
8
3105p
Introduction
The LTC3105 is a unique, high performance, synchronous
boost converter that incorporates maximum power pointcontrol, 250mV start-up capability and an integrated LDOregulator. This part operates over a very wide range ofinput voltages from 0.2V to 5V. Its Burst Mode architectureand low 22A quiescent current optimize efficiency in lowpower applications.
An integrated maximum power point controller allows foroperation directly from high impedance sources such asphotovoltaic cells by preventing the input power source volt-age from collapsing below the user programmable MPPCthreshold. Peak current limits are automatically adjusted
with proprietary techniques to maintain operation at levelsthat maximize power extraction from the source.
The 250mV start-up voltage and 200mV minimum operat-ing voltage enable direct operation from a single photovol-taic cell and other very low voltage, high series impedancepower sources such as TEGs and fuel cells.
Synchronous rectification provides high efficiency opera-tion while eliminating the need for external Schottky diodes.The LTC3105 provides output disconnect which preventslarge inrush currents during start-up. This is particularly
important for high internal resistance power sources likephotovoltaic cells and thermoelectric generators whichcan become overloaded if inrush current is not limitedduring start-up of the power converter. In addition, outputdisconnect isolates VOUT from VIN while in shutdown.
VIN > VOUT Operation
The LTC3105 includes the ability to seamlessly maintainregulation if VIN becomes equal to or greater than VOUT.With VIN greater than or equal to VOUT, the synchro-nous rectifiers are disabled which may result in reduced
efficiency.
Shutdown Control
The SHDN pin is an active low input that places the ICinto low current shutdown mode. This pin incorporates aninternal 2M pull-up resistor which enables the converterif the SHDN pin is not controlled by an external circuit.The thresholds for the SHDN pin change dynamically withthe maximum of VIN and VAUX. At low system voltages
OPERATION
(VIN and VAUX), the shutdown pin thresholds are as lowas 50mV from the voltage rails. See the curves in theTypical Performance Characteristics section of this data
sheet for more information on SHDN threshold variationswith system voltages. In shutdown, the internal switchconnecting AUX and VOUT is enabled.
When the SHDN pin is released, the LTC3105 is enabledand begins switching after a short delay. When either VINorVAUX is above 1.4V, this delay will typically range between20s and 100s. At lower voltages, this delay can be upto several milliseconds. Refer to the Typical PerformanceCharacteristics section for more details.
Start-Up Mode Operation
The LTC3105 provides the capability to start with voltagesas low as 250mV. During start-up the AUX output initiallyis charged with the synchronous rectifiers disabled. OnceVAUXhas reached approximately 1.4V, the converter leavesstart-up mode and enters normal operation. Maximumpower point control is not enabled during start-up, however,the currents are internally limited to sufficiently low levelsto allow start-up from weak input sources.
While the converter is in start-up mode, the internal switchbetween AUX and VOUT remains disabled and the LDO
is disabled. Refer to Figure 1 for an example of a typicalstart-up sequence.
Normal Operation
When either VIN or VAUX is greater than 1.4V typical, theconverter will enter normal operation.
The converter continues charging the AUX output untilthe LDO output enters regulation. Once the LDO outputis in regulation, the converter begins charging the VOUTpin. VAUX is maintained at a level sufficient to ensure the
LDO remains in regulation. If VAUX becomes higher thanrequired to maintain LDO regulation, charge is transferredfrom the AUX output to the VOUT output. If VAUX falls toolow, current is redirected to the AUX output instead ofbeing used to charge the VOUT output. Once VOUT risesabove VAUX, an internal switch is enabled to connect thetwo outputs together.
If VIN is greater than the voltage on the driven output (VOUTor VAUX), or the driven output is less than 1.2V (typical),
8/8/2019 LTC3105 Datasheet
9/16
LTC3105
9
3105p
3105 F01
OUTPUT
VOLTAGE
INDUCTOR
CURRENT
TIME
TIME
NORMAL OPERATION
LDO IN
REGULATION
1.4V
VOUT SYNCHRONOUS
RECTIFIER ENABLED
VAUX VOUT
VOUT IN
REGULATION
VOUT = VAUX
START-UP MODE
VLDO
the synchronous rectifiers are disabled. With the synchro-nous rectifiers disabled, the converter operates in criticalconduction mode. In this mode, the N-channel MOSFETbetween SW and GND is enabled and remains on until theinductor current reaches the peak current limit. It is thendisabled and the inductor current discharges completelybefore the cycle is repeated.
When the output voltage is greater than the input voltageand greater than 1.2V, the synchronous rectifier is enabled.In this mode, the N-channel MOSFET between SW andGND is enabled until the inductor current reaches the peak
current limit. Once current limit is reached, the N-channelMOSFET turns off and the P-channel MOSFET between SWand the driven output is enabled. This switch remains onuntil the inductor current drops below the valley currentlimit and the cycle is repeated.
When VOUT reaches the regulation point, the N- and P-channel MOSFETs connected to the SW pin are disabledand the converter enters sleep.
Figure 1. Typical Converter Start-Up Sequence
Auxiliary LDO
The integrated LDO provides a regulated 6mA rail topower microcontrollers and external sensors. The LDO ispowered from the AUX output allowing the LDO to attainregulation while the main output is still charging. The LDOhas a 12mA current limit and an internal 1ms soft-startto eliminate inrush currents. The LDO output voltage isset by the FBLDO pin. If a resistor divider is connectedto this pin, the ratio of the resistors determines the LDOoutput voltage. If the FBLDO pin is connected directly toGND, the LDO will use a 2M internal divider network to
program a 2.2V nominal output voltage. The LDO shouldbe programmed for an output voltage less than the pro-grammed VOUT.
When the converter is placed in shutdown mode (dueto undervoltage lockout or via the SHDN pin) the LDO isforced into reverse-blocking mode with reverse currentlimited to under 1A. After the shutdown event has ended,the LDO remains in reverse-blocking mode until VAUX hasrisen above the LDO voltage.
OPERATION
8/8/2019 LTC3105 Datasheet
10/16
LTC3105
10
3105p
MPPC Operation
The maximum power point control circuit allows the user
to set the optimal input voltage operating point for a givenpower source. The MPPC circuit dynamically regulatesthe average inductor current to prevent the input voltagefrom dropping below the MPPC threshold. When VIN isgreater than the MPPC voltage, the inductor current isincreased until VIN is pulled down to the MPPC set point.If VIN is less than the MPPC voltage, the inductor currentis reduced until VIN rises to the MPPC set point.
Automatic Power Adjust
The LTC3105 incorporates a feature that maximizes ef-
ficiency at light load while providing increased powercapability at heavy load by adjusting the peak and valleyof the inductor current as a function of load. Lowering thepeak inductor current to 100mA at light load optimizesefficiency by reducing conduction losses. As the loadincreases, the peak inductor current is automatically in-creased to a maximum of 400mA. At intermediate loads,the peak inductor current can vary between 100mA to400mA. This function is overridden by the MPPC functionand will only be observed when the power source candeliver more power than the load requires.
PGOOD Operation
The power good output is used to indicate that VOUT is
in regulation. PGOOD is an open-drain output, and isdisabled in shutdown and undervoltage lockout. PGOODwill indicate that power is good at the beginning of thefirst sleep event after the output voltage has risen above90% of its regulation value. PGOOD remains asserted untilVOUT drops below 90% of its regulation value at whichpoint PGOOD will pull low.
Input Undervoltage Lockout
In applications such as photovoltaic conversion, the inputpower source may be absent for long periods of time.
To minimize discharge of the outputs in such cases, theLTC3105 incorporates an undervoltage lockout (UVLO)which forces the converter into shutdown mode if theinput voltage falls below 90mV (typical). In shutdown,the switch connecting AUX and VOUT is enabled andthe LDO is placed into reverse-blocking mode and thecurrent into VOUT is reduced to 4A typical. Reverse cur-rent through the LDO is limited to 1A in shutdown tominimize discharging of the output. Refer to the TypicalPerformance Characteristics curves for details on thereverse current into VOUT.
OPERATION
Component Selection
Low DCR power inductors with values between 4.7Hand 30H are suitable for use with the LTC3105. Formost applications, a 10H inductor is recommended. Inapplications where the input voltage is very low, a largervalue inductor can provide higher efficiency and a lower
start-up voltage. In applications where the input voltageis relatively high (VIN > 0.8V), smaller inductors may beused to provide a smaller overall footprint. In all cases,the inductor must have low DCR and sufficient saturationcurrent rating. If the DC resistance of the inductor is toohigh, efficiency will be reduced and the minimum operatingvoltage will increase.
Input capacitor selection is highly important in low voltage,high source resistance systems. For general applications,
APPLICATIONS INFORMATION
a 10F ceramic capacitor is recommended between VINand GND. For high impedance sources, the input capacitorshould be large enough to allow the converter to completestart-up mode using the energy stored in the input ca-pacitor. When using bulk input capacitors that have highESR, a small valued parallel ceramic capacitor should be
placed between VIN and GND as close to the converterpins as possible.
A 1F ceramic capacitor should be connected betweenAUX and GND. Larger capacitors should be avoided tominimize start-up time. A low ESR output capacitor shouldbe connected between VOUT and GND. The main outputcapacitor should be 10F or larger. The main output canalso be used to charge energy storage devices includingtantalum capacitors, supercapacitors and batteries. When
8/8/2019 LTC3105 Datasheet
11/16
LTC3105
11
3105p
APPLICATIONS INFORMATIONusing output bulk storage devices with high ESR, a smallvalued ceramic capacitor should be placed in parallel andlocated as close to the converter pins as possible.
Step-Up Converter Feedback Configuration
A resistor divider connected between the VOUT and FB pinsprograms the step-up converter output voltage, as shownin Figure 2. An optional 22pF feedforward capacitor, CFF1,can be used to reduce output ripple and improve loadtransient response. The equation for VOUT is:
VOUT = 1.008V
R1
R2+ 1
LDO Regulator Feedback Configuration
Two methods can be used to program the LDO outputvoltage, as shown in Figure 3. A resistor divider connectedbetween the LDO and FBLDO pins can be used to programthe LDO output voltage. The equation for the LDO outputvoltage is:
VLDO = 1.008V
R3
R4+ 1
Figure 2. FB Configuration
3105 F02
LTC3105CFF1 R1
R2
FB
VOUT
Figure 3. FBLDO Configuration
3105 F03
LDO
LTC3105R3
2.2V
R4
LDO
FBLDO FBLDO
LTC3105
Alternatively, the FBLDO pin can be connected directly toGND. In this configuration, the LDO is internally set to anominal 2.2V output.
MPPC Threshold Configuration
The MPPC circuit controls the inductor current to main-tain VIN at the voltage on the MPPC pin. The MPPC pinvoltage is set by connecting a resistor between the MPPCpin and GND, as shown in Figure 4. The MPPC voltage isdetermined by the equation:
VMPPC = 10A RMPPC
In photovoltaic cell applications, a diode can be used toset the MPPC threshold so that it tracks the cell voltageover temperature, as shown in Figure 5. The diode shouldbe thermally coupled to the photovoltaic cell to ensureproper tracking. A resistor placed in series with the diodecan be used to adjust the DC set point to better matchthe maximum power point of a particular source if theselected diode forward voltage is too low. If the diode islocated far from the converter inputs, a capacitor may berequired to filter noise that may couple onto the MPPCpin, as shown in Figure 5. This method can be extendedto stacked cell sources through use of multiple series
connected diodes.
Figure 4. MPPC Configuration
Figure 5. MPPC Configuration with Temperature Adjustment
3105 F04
MPPC
LTC3105RMPPC
10A
3105 F05
MPPC
LTC3105
C610nF
VFWD
RMPPC
10A
+
8/8/2019 LTC3105 Datasheet
12/16
LTC3105
12
3105p
TEMPERATURE (C)
45
MPPCVOLTAGE(V)
0.4
15 15 45
0.2
0.3
0.7
0.1
0
0.6
0.5
30 0 75 9030 60
3105 TA02aTIME (s)
0 25 50 75 100 125 150
3105 TA02b
INPUT CURRENT25mA/DIV
OUTPUT CURRENT5mA/DIV
INPUT VOLTAGE50mV/DIV
VOUT = 2.8VVMPPC = 0.4VVFB = 0.94V
APPLICATIONS INFORMATION
Industrial Current Loops
The low 250mV start-up and low voltage operation of the
LTC3105 allow it to be supplied by power from a diodeplaced in an industrial sensor current loop, as shownin Figure 6. In this application, a large input capacitoris required due to the very low available supply current(less than 4mA). The loop diode should be selected for aminimum forward drop of 300mV. The MPPC pin voltageshould be set for a value approximately 50mV below theminimum diode forward voltage.
Figure 6. Current Loop Power Tap
3105 F06
GND
MPPC
VIN
LTC3105
CINVFWD
RMPPC
4mA TO 20mA
CURRENT LOOP+
3.3V from a Single-Cell Photovoltaic Source with Temperature Tracking
VMPPC vs Temperature Input Current Step Response
3105 TA02
COUT10F
R12.26M
VOUT3.3V
R21M
FB
PGOOD
LDO
FBLDO
MPPC
SHDN
AUX
SW
CLDO4.7F
2.2VRMPPC9.09k
CAUX1F
* MRA4003T3** COILCRAFT MSS5131-103MX
LTC3105
CMPPC10nF GND
CIN10F
L1**10H
+
ONOFF
VIN
VOUT
D1*
THERMALLYCOUPLED
TYPICAL APPLICATIONS
8/8/2019 LTC3105 Datasheet
13/16
LTC3105
13
3105p
TYPICAL APPLICATIONS
3.3V from Multiple Stacked-Cell Photovoltaic with Source Temperature Tracking
Thermoelectric Generator to 2.4V Super Capacitor Charger
3105 TA03
COUT10F
R11.37M
VOUT3.3V
R2604k
FB
PGOOD
LDO
FBLDO
MPPC
SHDN
AUX
SW
CLDO4.7F
2.2V
CAUX1F
RMPPC4.99k
CIN10F
* MRA4003TE** PANASONIC ELL-VEG6R8N
L1**6.8H
LTC3105
CMPPC10nF
GND
+
+
ONOFF
VIN
VOUT
D1*
D2*
THERMALLYCOUPLED
3105 TA04
CBULK1F2.5V
R11.10M
VOUT2.4V
R2787k
FB
PGOOD
LDO
FBLDO
MPPC
VIN
SHDN
AUX
SW
VOUT
CLDO4.7F
2.2V
CFF22pF
RMPPC30.1k
* MICROPELT MPG-D751** COILCRAFT MSS5131-103MX
TEG*
T 10C
CAUX1F
CIN100F
L1**10H
LTC3105
GND
COUT1F
ONOFF
+
+
8/8/2019 LTC3105 Datasheet
14/16
LTC3105
14
3105p
TIME (ms)
0 6 12 18 24 30 36 42 48
3105 TA05a
VIN VOLTAGE500mV/DIV
LDO VOLTAGE50mV/DIV
LOAD CURRENT2mA/DIV
VOUT VOLTAGE500mV/DIV
TIME (ms)
0 50 100 150 200 250 300
3105 TA05b
VIN VOLTAGE200mV/DIV
LDO VOLTAGE500mV/DIV
VOUT VOLTAGE500mV/DIV
TYPICAL APPLICATIONS
Industrial Sensor 4mA to 20mA Current Loop Power Tap
VOUT, VIN, LDO and IOUT Burst Load Start-Up VIN, VOUT, VLDO
3105 TA05
R12M
VOUT, 3V
R21M
FB
ENPGOOD
LDO
FBLDO
MPPC
SHDN
AUX
SW
P
CAUX1F
RMPPC28k
280mV
2.2V
CIN470F
4mA TO 20mACURRENT LOOP
D1*
L1**10H
LTC3105
GND
10F
VFWD = 330mV
RPG499k
* MBRS190T3** COILCRAFT MSS5131-103MX
+
ONOFF
VIN
VDD
VOUT
CLDO4.7F
Single-Cell Photovoltaic NiMH Trickle Charger
3105 TA06
NiMH 2
R11.02M
VOUT3.2V
R2470k
FB
PGOOD
LDO
FBLDO
MPPC
SHDN
AUX
SW
CLDO4.7F
1.8V
RMPPC40.2k
CAUX1F
CIN10F
L1, 10H
LTC3105
GND
COUT10F
R31M
R41.27M
+
+
+
ONOFF
VIN
VOUT
8/8/2019 LTC3105 Datasheet
15/16
LTC3105
15
3105p
PACKAGE DESCRIPTION
DD Package10-Lead Plastic DFN (3mm 3mm)
(Reference LTC DWG # 05-08-1699 Rev B)
3.00 0.10(4 SIDES)
NOTE:1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION
OF (WEED-2). CHECK THE LTC WEBSITE DATA SHEET FOR CURRENTSTATUS OF VARIATION ASSIGNMENT
2. DRAWING NOT TO SCALE3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE5. EXPOSED PAD SHALL BE SOLDER PLATED6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE
TOP AND BOTTOM OF PACKAGE
0.40 0.10
BOTTOM VIEWEXPOSED PAD
1.65 0.10(2 SIDES)
0.75 0.05
R = 0.125TYP
2.38 0.10(2 SIDES)
15
106
PIN 1TOP MARK
(SEE NOTE 6)
0.200 REF
0.00 0.05
(DD)DFN REV B 0309
0.25 0.05
2.38 0.05(2 SIDES)
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
1.65 0.05(2 SIDES)2.15 0.05
0.50BSC
0.70 0.05
3.55 0.05PACKAGEOUTLINE
0.25 0.050.50 BSC
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
MSOP (MS12) 1107 REV
0.53 0.152
(.021
.006)
SEATINGPLANE
0.18
(.007)
1.10(.043)MAX
0.22 0.38
(.009 .015)TYP
0.86(.034)REF
0.650
(.0256)BSC
12 11 10 9 8 7
NOTE:1. DIMENSIONS IN MILLIMETER/(INCH)2. DRAWING NOT TO SCALE3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS.
MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.
INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE5. LEAD COPLANARITY (BOTTOM OF LEADS AF TER FORMING) SHALL BE 0.102mm (.004") MAX
0.254
(.010)0 6 TYP
DETAIL A
DETAIL A
GAUGE PLANE
5.23(.206)MIN
3.20 3.45(.126 .136)
0.889 0.127(.035 .005)
RECOMMENDED SOLDER PAD LAYOUT
0.42 0.038(.0165 .0015)
TYP
0.65(.0256)
BSC
4.039 0.102
(.159 .004)(NOTE 3)
0.1016 0.0508
(.004 .002)
1 2 3 4 5 6
3.00 0.102
(.118 .004)(NOTE 4)
0.406 0.076
(.016 .003)REF
4.90 0.152
(.193 .006)
MS Package12-Lead Plastic MSOP
(Reference LTC DWG # 05-08-1668 Rev )
8/8/2019 LTC3105 Datasheet
16/16
LTC3105
3105p
Linear Technology CorporationLT 1010 PRINTED IN USA
RELATED PARTS
TYPICAL APPLICATION
PART NUMBER DESCRIPTION COMMENTS
LTC3108/LTC3108-1 Ultralow Voltage Step-Up Converter and PowerManager
VIN : 0.02V to 1V; VOUT = 2.2V, 2.35V, 3.3V, 4.1V, 5V; IQ = 6A; 4mm 3mmDFN-12, SSOP-16 Packages; LTC3108-1 VOUT = 2.2V, 2.5V, 3V, 3.7V, 4.5V
LTC3109 Auto-Polarity, Ultralow Voltage Step-Up
Converter and Power Manager
|VIN |: 0.03V to 1V; VOUT = 2.2V, 2.35V, 3.3V, 4.1V, 5V; IQ = 7A; 4mm 4mm
QFN-20, SSOP-20 PackagesLTC4070 Li-Ion/Polymer Shunt Battery Charger System 450nA IQ; 1% Float Voltage Accuracy; 50mA Shunt Current 4.0V/4.1V/4.2V
LTC4071 Li-Ion/Polymer Shunt Battery Charger Systemwith Low Battery Disconnect
550nA IQ; 1% Float Voltage Accuracy;