DEMO MANUAL DC1923A
LTC3129-1
15V, 200mA Synchronous Buck-Boost DC/DC
Converter with 1.3µA Quiescent Current
Description
Demonstration circuit 1923A features the
LTC3129-1,
a
high efficiency 200mA buck-boost DC/DC converter with
a wide V
IN
and V
OUT
range.
The DC1923A demo board has two user selectable operat-
ing modes: Burst Mode
®
operation and fixed frequency
PWM (JP3). There is also an accurate programmable RUN
pin which is used to ENABLE the converter (JP1). The
LTC3129-1 also incorporates a maximum power point
control function which can be enabled (JP2) for applications
where the input source is a solar cell or is high imped-
ance, such as intrinsically safe applications or high Z
OUT
thermal electric generators (TEGs). The LTC3129-1 also
features fixed output voltages with eight user-selectable
settings (JP4, JP5, JP6). This allows the user to eliminate
the output voltage divider and the associated bias current.
The DC1923A operates with a 2.42V to 15V input voltage
range, and has been designed with the output voltage set
to 5V. The demo board can be programmed to any of the
eight voltage settings by using jumpers JP4, JP5, and JP6.
Once the converter is started the LTC3129-1 can operate
with V
IN
as low as 1.92V provided V
CC
is back-fed. Consult
the data sheet for more information on these options.
The DC1923A demo board also incorporates a connector
(J1) which can be used to connect to a Dust Networks
®
mote demo board.
Figure 1 shows typical demo board efficiency and Figure 2
shows typical step response.
The LTC3129-1 data sheet has detailed information about
the operation, specification, and applications of the part.
The data sheet should be read in conjunction with this
quick start guide.
Design files for this circuit board are available at
http://www.linear.com/demo
L,
LT, LTC, LTM, Linear Technology, the Linear logo, Burst Mode, Dust Networks and Dust are
registered trademarks of Linear Technology Corporation. All other trademarks are the property
of their respective owners.
performance summary
PARAMETER
Input Voltage Range
VOUT
IOUT (see Note 1)
Efficiency
Specifications are at T
A
= 25°C
TYPICAL
2.42V to 15V
5V; 8 User Selectable Voltages
200mA, for VIN > V
OUT
See Figure 1
Note 1: The demo board output current is a function of VIN. Please refer to the data sheet for more information.
dc1923af
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DEMO MANUAL DC1923A
Description
DC1923A Efficiency vs Load, V
OUT
= 5V
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
0.01
0.1
1
10
LOAD (mA)
PWM
V
IN
= 3V
V
IN
= 5V
V
IN
= 10V
V
IN
= 15V
100
1000
AutoBURST
Figure 1. DC1923A Efficiency
Figure 2. DC1923A 50mA to 100mA Output Step Response
Quick start proceDure
Using short twisted pair leads for any power connections
and with all loads and power supplies off, refer to Figure 3
for the proper measurement and equipment setup. The
power supply (PS1) should not be connected to the circuit
until told to do so in the procedure below.
When measuring the input or output voltage ripple, care
must be taken to avoid a long ground lead on the oscil-
loscope probe. Measure the input or output voltage ripple
by touching the probe tip directly across the VIN or VOUT
and GND terminals (see Figure 4), or by using an oscil-
loscope probe tip jack.
1. Jumper, PS1 and LOAD settings to start:
PS1:
JP1:
JP2:
JP3:
JP7:
JP4:
JP5:
JP6:
RUN
MPPC
PWM
OFF
ON
OFF
BURST MODE
DUST PWR NC
VS1
VS2
VS3
VCC
VCC
GND
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To set VOUT = 5V
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DEMO MANUAL DC1923A
Quick start proceDure
2. With power OFF connect the power supply (PS1) as
shown in Figure 3. If accurate current measurements
are desired (for efficiency calculations for example) then
connect an ammeter (AM1) in series with the supply
as shown. The ammeter is not required however.
3. Connect a 50mA load to VOUT as shown in Figure 3
(100Ω for VOUT = 5V). Connect an ammeter (AM2)
if accurate current measurement or monitoring is
desired.
4. Turn on PS1 and slowly increase voltage until the
voltage at VIN is 4V.
5. Verify VOUT is ~5V.
6. VIN can now be varied between 2.42V and 15V. VOUT
should remain in regulation.
7. Load current (IOUT) can also be varied. The maximum
IOUT is a function of VIN and the current limit. Consult
the data sheet for more information on IOUT vs VIN.
In general for VIN > VOUT IOUT can be increased to
200mA. For VIN < VOUT IOUT capability will be reduced.
8. For operation in fixed frequency (PWM) mode move
Jumper JP3 to FIXED FREQ. See the data sheet for
more information on Burst Mode operation.
9. NOTE: If VOUT drops out of regulation, check to be
sure that VIN is not below the minimum value for
regulation (see data sheet).
For USE with a Solar Cells/MPPC:
10. With power OFF move jumper MPPC (JP2) to ON.
11. If using a power supply as the source, place a mini-
mum of 10Ω, 10W resistor in series with the input to
simulate the source resistance. If using a solar cell(s)
or high impedance source, no additional resistance
should be needed.
12. Set resistor R6 to a value which will set the MPPC
pin to the desired voltage. See the data sheet section
Programming the MPPC Voltage for more information.
13. With no load and the MPPC voltage set, increase the
source voltage above the MPPC set point. VOUT should
be in regulation. As the load is increased VIN will drop
until it reaches the MPPC set voltage. As the load is
increased further, VOUT will drop out of regulation,
but VIN will be regulated to the set point voltage. This
is to prevent the input source from collapsing and to
allow the maximum power to be extracted from the
source.
14. Consult the data sheet for more information on maxi-
mum power point control (MPPC) operation.
For USE with a DUST Networks MOTE demo board:
15. Connector J1 is designed to interface with a Dust
Networks mote demo board. Consult the Dust
®
documentation for optimal VOUT regulation setting.
In general the Dust Networks mote will operate with
VOUT set to 3.3V. However, care should be taken to
not overvoltage the mote. Newer motes may require
a different VOUT. The DC1923A demo board can be
configured for different VOUT voltages by simply
changing jumpers JP4, JP5 and JP6. To configure the
board for 3.3V set the jumpers as follows:
JP4:
JP5:
JP6:
VS1
VS2
VS3
VCC
GND
GND
16. Once the output voltage has been set to the proper volt-
age and with the power supply OFF connect DC1923A
to the Dust Networks mote demo board using J1.
See Figures 5 and 6 for the proper connections and
orientation. Move jumper JP7 to VOUT.
17. Once the boards have been connected, turn on PS1
and increase the voltage to approximately 3V. VOUT
should now be in regulation. VIN can now be varied
over the operating range and VOUT should remain in
regulation.
dc1923af
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DEMO MANUAL DC1923A
Quick start proceDure
Figure 3. Proper Measurement Equipment Setup
Figure 4. Measuring Input or Output Ripple
Figure 5. DC1923A Connected to DC9003A Dust Mote (Top View)
dc1923af
VIN
GND
4
DEMO MANUAL DC1923A
Quick start proceDure
Figure 6. DC1923A Connected to DC9003A Dust Mote (Bottom View)
parts List
ITEM
1
2
3
4
5
6
7
8
9
10
QTY
1
2
1
2
1
1
1
1
3
1
REFERENCE
C1
C2, C4
C3
C5, C6
C9
C10
L1
Q1
R1, R2, R4
U1
PART DESCRIPTION
CAP CER 22µF 25V X5R 20% 1210
CAP CER 1µF 25V X5R 0603
CAP CER 10µF 25V X5R 1210
CAP CER 22000pF 50V X7R 10% 0603
CAP CER 2.2µF 10V X7R 20% 0603
CAP CER 10pF 50V NP0 ±0.25pF 0603
INDUCTOR, 10µH
N-CHANNEL MOSFET, 20V, SOT23
RES, CHIP, 2M, 1/16W, 1%, 0402
15V, 200mA SYNCHRONOUS BUCK-BOOST DC/DC
CONVERTER WITH 1.3µA QUIESCENT CURRENT
CAP CER 0603
CAP TANT 68µF 20V 10% SMD 7343
RES 1/10W 1% 0402 SMD
TESTPOINT, TURRET 0.094"
HEADER, 2X6, 12-PIN, SMT HORIZONTAL SOCKET w/KEY,
0.100"
JMP, 0.079" SINGLE ROW HEADER, 3 PIN
SHUNT, 0.079" CENTER
STAND-OFF, NYLON 0.625" TALL
MANUFACTURER/PART NUMBER
TDK, C3225X5R1E226M
TDK, C1608X5R1E105M
TDK, C3225X5R1E106M
TDK, C1608X7R1H223K
TDK, C1608X7R1A225M
TDK, C1608C0G1H100C
COILCRAFT, EPL3015-103
DIODES/ZETEX, ZXMN2F30FHTA
VISHAY, CRCW04022M00FKED
LINEAR TECHNOLOGY, LTC3129EUD-1
Required Circuit Components
Additional Demo Board Circuit Components
1
2
3
1
2
3
4
5
0
0
0
5
1
7
7
4
C7 (OPT)
C8 (OPT)
R3, R5, R6 (OPT)
E1, E2, E3, E4, E5
J1
JP1-JP7
XJP1-XPJP7
(STAND-OFFS)
OPT
OPT
OPT
MILLMAX 2501-2-00-80-00-00-07-0
SAMTEC, SMH-106-02-L-D-05
SAMTEC, TMM-103-02-L-S
SAMTEC, 2SN-BK-G
KEYSTONE, 8834(SNAP ON)
Hardware: For Demo Board Only
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