DEMO MANUAL DC1587
LTC3105EDD: Step-Up
DC/DC Converter with Power
Point Control and LDO Regulator
DESCRIPTION
Demonstration circuit 1587A is a boost converter optimized for relatively high impedance, very low voltage
input power sources. It allows a user to quickly evaluate
the LTC3105 boost converter and LDO regulator. Capableof operating with an input voltage as low as 250mV andas high as 5V, the circuit features maximum power pointcontrol (MPPC). Jumpers on the circuit board allow theuser to select several MPPC voltages, three boost output
voltages and three LDO regulator output voltages. Also
included are jumpers for shutdown and for selecting an
external pull-up voltage for the power good status output.
Terminals are provided for input and output connections,power good output and external power good supply input,
shutdown input, and provisions for external MPPC resistor
and MPPC diode input.
This demonstration board is especially designed for low
power solar cell applications. The LTC3105 data sheet
gives a complete description of the part, operation andapplication information. The data sheet must be read in
conjunction with this demo manual.
Design ﬁles for this circuit board are available at
http://www.linear.com/demo
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.

PERFORMANCE SUMMARY (T = 25°C)
APARAMETERCONDITION

VALUE

Start-Up Input Voltage

No Load, RMPPC = 22k, Supply ESR = 0.5Ω, See Section 3250mV TypicalInput Voltage Range

After Start-Up

0.2V to 5V

Maximum Boost Output Current

VIN = 2V, VOUT = 5V, MPPC = 2V, Resistive Load

125mA

1.8V Boost Output Voltage

VIN = 1.5V, 100Ω Load

1.8V ±3%3.3V Boost Output Voltage

VIN = 1.5V, 100Ω Load

3.3V ±3%

5V Boost Output Voltage

VIN = 1.5V, 100Ω Load

5V ±3%

1.5V LDO Output Voltage

VIN = 1.5V, 500Ω Load

1.5V ±3%2.2V LDO Output Voltage

VIN = 1.5V, 500Ω Load

2.2V ±2%

3V LDO Output Voltage

VIN = 1.5V, 500Ω Load3V ±3%QUICK START PROCEDURE
Equipment required to evaluate the LTC3105 demonstration
circuit include a low voltage bench power supply, digital
voltmeters and suitable load resistors. Refer to Figure 1for proper measurement equipment setup and follow theprocedure below.

1. Begin by placing jumpers in the following positions.
JP4
PGOOD

JP1
BOOST

JP3
LDO

JP2
MPPC

JP5
SHDN

VPGOOD

5V

3V

0.4V

OFFdc1587f

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DEMO MANUAL DC1587
QUICK START PROCEDURE
2. With the power off, connect a low voltage adjustable
power supply and three voltmeters as shown in Figure 1(ammeters are optional). Switch the power supply onand adjust the voltage to approximately 450mV, andmove the JP5 jumper to the ON position. With no load
resistor on either output, verify that the BOOST and LDO
output voltages are within the speciﬁcations shown inTable 1. Increase the input voltage to 1.5V and connect
suitable load resistors to the output terminals to verify
the output voltages under load. The maximum Boost
output current is dependant on VIN and the maximum
LDO output current is 6mA
Maximum power point control (MPPC) prevents theconverter from pulling the input supply voltage down
below a preset voltage level when the maximum input
supply current is reached. The converter does this by
dynamically reducing the converter’s output voltage

and current as the input voltage begins to drop dueto the input power source current limitations. Without
MPPC, a converter would pull the input power source
down to near 0V, resulting in near zero output power.
MPPC is especially useful with power sources that haverelatively high or variable source impedances such as
solar cells and other energy harvesting devices. The
following exercise is to illustrate the MPPC function.
To demonstrate the MPPC function, place a 10Ω, 1W
resistor in series with the demo board input terminal(VIN) to simulate a high impedance power source. Movejumper JP2 (MPPC) to the 2V position and jumpers JP1and JP3 to the 5V and 3V positions respectively andconnect voltmeters to measure VIN and boost VOUT.
With the power supply set to 3.5V, apply voltage to theinput. With an adjustable load on the boost output,
begin increasing the load on the 5V output.

Figure 1. Proper Measurement Equipment Setup

dc1587f2

DEMO MANUAL DC1587
QUICK START PROCEDURE
As the output load current increases, the voltage on
VIN decreases due to the 10Ω input resistor. Figure 2
shows VIN, VOUT and PGOOD voltages as the loadcurrent is increased over a 2 second time period withthe MPPC programmed for 2V. The output remains ata regulated 5V until the input voltage drops to the 2V
MPPC threshold. The MPPC prevents the input voltage
from dropping below 2V by reducing the output voltage. Without MPPC, the output voltage would drop tonear 0V resulting in zero output power. Connecting theMPPC pin to GND will disable the MPPC function. Also
shown in Figure 1 is the Power Good (PGOOD) signalthat pulls low when the Boost output voltage drops
10% below the programmed value.
3.5
VIN
3.0
VIN (V)

2.0
6

1.5
VOUT (2V/DIV)BOOST VOUT (V)LOAD CURRENT(20mA/DIV)

2.5

minal and ground. Connect a resistor of approximately
0.5Ω between the supply output and VIN. Adjust thesupply to approximately 250mV to 300mV and verify
that the boost output is in regulation. Since this DC/DC
converter is designed to operate from relatively highimpedance power sources, some source resistance is
neccessary for proper low voltage start-up. At very low
input voltage, excessive input current may result unlessthere is some source resistance.
4. Additional demo board features include the following.
Jumper JP4 allows the PGOOD open drain FET pull-up
resistor to be connected to the LDO output voltage orto an external voltage applied to the VPGOOD terminal. The converter can be shutdown by pulling SHDN
terminal low. MPPC jumper allows the user to selectseveral preset MPPC voltages or select the DIODE terminal when using diodes located near the solar panel
for MPPC temperature tracking. A small circular padon the board allows the LTC3105 AUX pin to be probed
when evaluating the circuit. Do not connect a load tothis pad.

42PGOOD SIGNAL

02 SECONDS
dc1587 F02

Figure 2. Maximum Power Point Control Programmed for 2V,
Operating from a High Impedance Input Power Source (10Ω)

3. To verify very low voltage start-up (250mV to 300mV)
it is necessary to do the following; remove jumper JP2
and add an external 22k resistor between the MPPC ter-Figure 3. Correct Method For Measuring
Input or Output Voltage Ripple

dc1587f

3DEMO MANUAL DC1587
PARTS LISTITEM

QUANTITYREFERENCE

PART DESCRIPTIONMANUFACTURER, PART NUMBER

Required Circuit Components
11C1Capacitor, X5R, 10μF, 6.3V, 10%, 0805

AVX, 08056D106KAT2A

21C3Capacitor, X5R, 10μF, 16V, 10%, 0805

Taiyo Yuden, EMK212BJ106KG-T

31C5Capacitor, NPO, 33pF, 25V, 5%, 0402

AVX, 04023A330JAT2A

41C8Capacitor, X5R, 1μF, 16V, 10%, 0603

AVX, 0603YD105KAT2A

51L1Inductor, 10μH

Sumida, CDRH3D18NP-100N

61R1Resistor, Chip, 392k, 1/16W, 1%, 0402

Vishay, CRCW0402392KFKED

71R4Resistor, Chip, 499k, 1/16W, 1%, 0402

Vishay, CRCW0402499KFKED

81R6Resistor, Chip, 40.2k, 1/16W, 1%, 0402

Vishay, CRCW040240K2FKED

91R10Resistor, Chip, 100k, 1/16W, 1%, 0402

Vishay, CRCW0402100KFKED

101U1IC, LTC3105EDD, 3mm × 3mm DFN

Linear Technology, LTC3105EDD

Additional Circuit Components
10C2Tantalum, OPT

21C4Capacitor, X5R, 1μF, 16V, 10%, 0805

AVX, 0805YD105KAT2A

31C6Capacitor, NPO, 33pF, 25V, 5%, 0402

AVX, 04023A330JAT2A

41C7Capacitor, X5R, 4.7μF, 16V, 10%, 0805

Taiyo Yuden, EMK212BJ475MG-T

51C10Capacitor, X7R, 10nF, 50V, 10%, 0603

AVX, 06035C103KAT2A

61R2Resistor, Chip, 750k, 1/16W, 1%, 0402

Vishay, CRCW0402750KFKED

71R3Resistor, Chip, 845k, 1/16W, 1%, 0402

Vishay, CRCW0402845KFKED

81R5Resistor, Chip, 0, 0402

Vishay, CRCW04020000JKED

91R7Resistor, Chip, 200k, 1/16W, 1%, 0402

Vishay, CRCW0402200KFKED

101

R8Resistor, Chip, 402k, 1/16W, 1%, 0402

Vishay, CRCW0402402KFKED

11

1

R9Resistor, Chip, 549k, 1/16W, 1%, 0402

Vishay, CRCW0402549KFKED

12

1

R11Resistor, Chip, 274k, 1/16W, 1%, 0402

Vishay, CRCW0402274KFKED

131

R12Resistor, Chip, 1.1M, 1/16W, 1%, 0402

Vishay, CRCW04021M10FKED112E1-E12Testpoint, Turret, 0.095"

Mill-Max, 2501-2-00-80-00-00-07-0

22JP4, JP50.079 Single Row Header, 3-PinSamtec, TMM-103-02-L-S

Hardware

31JP22mm Double Row Header 4mm × 2mmSamtec, TMM-104-02-L-D

42JP1, JP32mm Double Row Header 2mm × 3mmSamtec, TMM-103-02-L-D

55JP1-JP5ShuntSamtec, 2SN-BK-G

dc1587f

4

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 representationthat the interconnection of its circuits as described herein will not infringe on existing patent rights.

ABC

E4E11MPPCDIODEVPGOOD

C1010nF
0603

R50TANT(OPT.)+C251. ALL RESISTORS ARE IN 0402
ALL CAPACITORS ARE IN 0402
2. INSTALL SHUNTS AS SHOWN.

NOTE: UNLESS OTHERWISE SPECIFIED

E10E9PGOOD

SHDN

E8E12E2GND

GND

E1+VIN
0.2V - 5V

R10100K
LDO

R640.2K
1%

R8402K
1%

JP5SHDN

SHDN

PGOOD

SW

AUX

FBLDOLDOFB

VOUTExposed Pad
Solder SideMPPC

VIN&86720(5127,&(4856U1LTC3105EDD

1032197C81uF
16V0603

C633pF

R4499K1%

C533pF

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R9549K
1%

R2750K
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1%JP2MPPC

C110uF
6.3V0805

L110uH
CDRH3D18NP-100N

31.8V
3.3V
5V

246135D

DIODE
0.4V
2V4V

2468
1357VLDO

4ON

123VPGOOD

123OFF

GND
11R3845K
1%

JP1BOOST

1.5V
2.2V
3V

246R121.1M
1%

JP3LDO(&2'$7(1$6,=(2GNDLDO OUTPUT
1.5V / 2.2V / 3V
@6mA

GND

BOOST OUTPUT
1.8V / 3.3V / 5V)5$1+

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DEMO MANUAL DC1587

SCHEMATIC DIAGRAM

dc1587f5DEMO MANUAL DC1587
DEMONSTRATION BOARD IMPORTANT NOTICE
Linear Technology Corporation (LTC) provides the enclosed product(s) under the following AS IS conditions:This demonstration board (DEMO BOARD) kit being sold or provided by Linear Technology is intended for use for ENGINEERING DEVELOPMENTOR EVALUATION PURPOSES ONLY and is not provided by LTC for commercial use. As such, the DEMO BOARD herein may not be completein terms of required design-, marketing-, and/or manufacturing-related protective considerations, including but not limited to product safetymeasures typically found in finished commercial goods. As a prototype, this product does not fall within the scope of the European Union directive on electromagnetic compatibility and therefore may or may not meet the technical requirements of the directive, or other regulations.
If this evaluation kit does not meet the specifications recited in the DEMO BOARD manual the kit may be returned within 30 days from the dateof delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVE WARRANTY MADE BY THE SELLER TO BUYER AND IS IN LIEU
OF ALL OTHER WARRANTIES, EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESSFOR ANY PARTICULAR PURPOSE. EXCEPT TO THE EXTENT OF THIS INDEMNITY, NEITHER PARTY SHALL BE LIABLE TO THE OTHER FOR
ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES.
The user assumes all responsibility and liability for proper and safe handling of the goods. Further, the user releases LTC from all claims
arising from the handling or use of the goods. Due to the open construction of the product, it is the user’s responsibility to take any and all
appropriate precautions with regard to electrostatic discharge. Also be aware that the products herein may not be regulatory compliant oragency certified (FCC, UL, CE, etc.).
No License is granted under any patent right or other intellectual property whatsoever. LTC assumes no liability for applications assistance,
customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind.
LTC currently services a variety of customers for products around the world, and therefore this transaction is not exclusive.
Please read the DEMO BOARD manual prior to handling the product. Persons handling this product must have electronics training andobserve good laboratory practice standards. Common sense is encouraged.
This notice contains important safety information about temperatures and voltages. For further safety concerns, please contact a LTC application engineer.
Mailing Address:
Linear Technology
1630 McCarthy Blvd.
Milpitas, CA 95035

Copyright © 2004, Linear Technology Corporation

dc1587f

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