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. Capable
of operating with an input voltage as low as 250mV and
as high as 5V, the circuit features maximum power point
control (MPPC). Jumpers on the circuit board allow the
user 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,
PERFORMANCE SUMMARY
PARAMETER
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 and
application 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.
(TA = 25°C)
CONDITION
VALUE
Start-Up Input Voltage
No Load, RMPPC = 22k, Supply ESR = 0.5Ω, See Section 3
250mV Typical
Input 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 Load
3V ±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 1
for proper measurement equipment setup and follow the
procedure 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
OFF
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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 on
and adjust the voltage to approximately 450mV, and
move 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 in
Table 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 the
converter 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 due
to 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 have
relatively 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. Move
jumper JP2 (MPPC) to the 2V position and jumpers JP1
and JP3 to the 5V and 3V positions respectively and
connect voltmeters to measure VIN and boost VOUT.
With the power supply set to 3.5V, apply voltage to the
input. With an adjustable load on the boost output,
begin increasing the load on the 5V output.
Figure 1. Proper Measurement Equipment Setup
dc1587f
2
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 load
current is increased over a 2 second time period with
the MPPC programmed for 2V. The output remains at
a 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 to
near 0V resulting in zero output power. Connecting the
MPPC pin to GND will disable the MPPC function. Also
shown in Figure 1 is the Power Good (PGOOD) signal
that 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 the
supply 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 high
impedance power sources, some source resistance is
neccessary for proper low voltage start-up. At very low
input voltage, excessive input current may result unless
there 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 or
to an external voltage applied to the VPGOOD terminal. The converter can be shutdown by pulling SHDN
terminal low. MPPC jumper allows the user to select
several preset MPPC voltages or select the DIODE terminal when using diodes located near the solar panel
for MPPC temperature tracking. A small circular pad
on the board allows the LTC3105 AUX pin to be probed
when evaluating the circuit. Do not connect a load to
this pad.
4
2
PGOOD SIGNAL
0
2 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
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DEMO MANUAL DC1587
PARTS LIST
ITEM
QUANTITY
REFERENCE
PART DESCRIPTION
MANUFACTURER, PART NUMBER
Required Circuit Components
1
1
C1
Capacitor, X5R, 10μF, 6.3V, 10%, 0805
AVX, 08056D106KAT2A
2
1
C3
Capacitor, X5R, 10μF, 16V, 10%, 0805
Taiyo Yuden, EMK212BJ106KG-T
3
1
C5
Capacitor, NPO, 33pF, 25V, 5%, 0402
AVX, 04023A330JAT2A
4
1
C8
Capacitor, X5R, 1μF, 16V, 10%, 0603
AVX, 0603YD105KAT2A
5
1
L1
Inductor, 10μH
Sumida, CDRH3D18NP-100N
6
1
R1
Resistor, Chip, 392k, 1/16W, 1%, 0402
Vishay, CRCW0402392KFKED
7
1
R4
Resistor, Chip, 499k, 1/16W, 1%, 0402
Vishay, CRCW0402499KFKED
8
1
R6
Resistor, Chip, 40.2k, 1/16W, 1%, 0402
Vishay, CRCW040240K2FKED
9
1
R10
Resistor, Chip, 100k, 1/16W, 1%, 0402
Vishay, CRCW0402100KFKED
10
1
U1
IC, LTC3105EDD, 3mm × 3mm DFN
Linear Technology, LTC3105EDD
Additional Circuit Components
1
0
C2
Tantalum, OPT
2
1
C4
Capacitor, X5R, 1μF, 16V, 10%, 0805
AVX, 0805YD105KAT2A
3
1
C6
Capacitor, NPO, 33pF, 25V, 5%, 0402
AVX, 04023A330JAT2A
4
1
C7
Capacitor, X5R, 4.7μF, 16V, 10%, 0805
Taiyo Yuden, EMK212BJ475MG-T
5
1
C10
Capacitor, X7R, 10nF, 50V, 10%, 0603
AVX, 06035C103KAT2A
6
1
R2
Resistor, Chip, 750k, 1/16W, 1%, 0402
Vishay, CRCW0402750KFKED
7
1
R3
Resistor, Chip, 845k, 1/16W, 1%, 0402
Vishay, CRCW0402845KFKED
8
1
R5
Resistor, Chip, 0, 0402
Vishay, CRCW04020000JKED
9
1
R7
Resistor, Chip, 200k, 1/16W, 1%, 0402
Vishay, CRCW0402200KFKED
10
1
R8
Resistor, Chip, 402k, 1/16W, 1%, 0402
Vishay, CRCW0402402KFKED
11
1
R9
Resistor, Chip, 549k, 1/16W, 1%, 0402
Vishay, CRCW0402549KFKED
12
1
R11
Resistor, Chip, 274k, 1/16W, 1%, 0402
Vishay, CRCW0402274KFKED
13
1
R12
Resistor, Chip, 1.1M, 1/16W, 1%, 0402
Vishay, CRCW04021M10FKED
1
12
E1-E12
Testpoint, Turret, 0.095"
Mill-Max, 2501-2-00-80-00-00-07-0
2
2
JP4, JP5
0.079 Single Row Header, 3-Pin
Samtec, TMM-103-02-L-S
Hardware
3
1
JP2
2mm Double Row Header 4mm × 2mm
Samtec, TMM-104-02-L-D
4
2
JP1, JP3
2mm Double Row Header 2mm × 3mm
Samtec, TMM-103-02-L-D
5
5
JP1-JP5
Shunt
Samtec, 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 representation
that the interconnection of its circuits as described herein will not infringe on existing patent rights.
A
B
C
E10
E9
E8
E12
E11
E4
E2
E1
C10
10nF
0603
R5
0
TANT
(OPT.)
+C2
5
1. ALL RESISTORS ARE IN 0402
ALL CAPACITORS ARE IN 0402
2. INSTALL SHUNTS AS SHOWN.
NOTE: UNLESS OTHERWISE SPECIFIED
SHDN
VPGOOD
PGOOD
GND
DIODE
MPPC
GND
+VIN
0.2V - 5V
R10
100K
LDO
R6
40.2K
1%
R8
402K
1%
JP5
SHDN
SHDN
PGOOD
SW
AUX
FBLDO
LDO
FB
VOUT
Exposed Pad
Solder Side
MPPC
VIN
&86720(5127,&(
4
8
5
6
U1
LTC3105EDD
10
3
2
1
9
7
C8
1uF
16V
0603
C6
33pF
R4
499K
1%
C5
33pF
4
3
7+,6&,5&8,7,635235,(7$5<72/,1($57(&+12/2*<$1'
6833/,(')2586(:,7+/,1($57(&+12/2*<3$576
R11
274K
1%
R9
549K
1%
R2
750K
1%
6&$/( 121(
)5$1+
-:
$33529$/6
R1
392K
1%
/,1($57(&+12/2*<+$60$'($%(67())25772'(6,*1$
&,5&8,77+$70((76&86720(56833/,('63(&,),&$7,216
+2:(9(5,75(0$,167+(&86720(5
65(63216,%,/,7<72 3&%'(6
9(5,)<3523(5$1'5(/,$%/(23(5$7,21,17+($&78$/
$33(1*
$33/,&$7,21&20321(1768%67,787,21$1'35,17('
&,5&8,7%2$5'/$<2870$<6,*1,),&$17/<$))(&7&,5&8,7
3(5)250$1&(255(/,$%,/,7<&217$&7/,1($5
7(&+12/2*<$33/,&$7,216(1*,1((5,1*)25$66,67$1&(
JP4
PGOOD
R7
200K
1%
JP2
MPPC
C1
10uF
6.3V
0805
L1
10uH
CDRH3D18NP-100N
3
1.8V
3.3V
5V
2
4
6
1
3
5
D
DIODE
0.4V
2V
4V
2
4
6
8
1
3
5
7
VLDO
4
ON
1
2
3
VPGOOD
1
2
3
OFF
GND
11
R3
845K
1%
JP1
BOOST
1.5V
2.2V
3V
2
4
6
R12
1.1M
1%
JP3
LDO
(&2
'$7(
1$
6,=(
2
GND
LDO OUTPUT
1.5V / 2.2V / 3V
@6mA
GND
BOOST OUTPUT
1.8V / 3.3V / 5V
)5$1+
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E7
E6
E5
E3
7XHVGD\1RYHPEHU
,&12
C7
4.7uF
16V
0805
TECHNOLOGY
LDO
C4
1uF
16V
0805
352'8&7,21
C3
10uF
16V
0805
'(6&5,37,21
5(9,6,21+,6725<
5(9
2
7,7/( 6&+(0$7,&
1
3
5
5
A
B
C
D
DEMO MANUAL DC1587
SCHEMATIC DIAGRAM
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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 DEVELOPMENT
OR EVALUATION PURPOSES ONLY and is not provided by LTC for commercial use. As such, the DEMO BOARD herein may not be complete
in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including but not limited to product safety
measures 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 date
of 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 FITNESS
FOR 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 or
agency 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 and
observe 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
6
Linear Technology Corporation
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