DC1429A - Demo Manual

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1429A
HIGH EFFICIENCY, HIGH VOLTAGE 50MA SYNCHRONOUS STEP-DOWN
CONVERTER
LTC3642
DESCRIPTION
Demonstration circuit DC1429A is a high efficiency
step-down DC/DC converter featuring LTC3642
with internal high side and synchronous power
switches that draws only 10µA quiescent current.
It has a wide 4.5V to 45V input range and internal
over voltage monitor capable of protecting the part
through 60V surges. The jumper selectable output
Table 1.
is up to 5V. LTC3642 can supply up to 50mA load
current with a programmable peak current limit
that provides a simple method for optimizing efficiency in lower current applications. With no compensation required, LTC3642 is easily configured
with minimal components. Gerber files for this
circuit are available. Call the LTC Factory.
Performance Summary (TA = 25ºC)
PARAMETER
CONDITION
VALUE
Input Voltage
Output Voltage VOUT
4.5V to 45V
IOUT=1mA to 50mA, VIN=10V
VOUT ± 2.7% (LTC3642 Output adjustable version)
VOUT ± 1.3% (LTC3642-3.3 Fixed 3.3V version)
VOUT ± 1.3% (LTC3642-5 Fixed 5.0V version)
Maximum Output Current
50mA
DC Supply Current
Active Mode, VIN=10V, IO=0A
110µA
Nominal Switching Frequency
Inductance=100µH, VIN=30V
350kHz
QUICK START PROCEDURE
The DC1429A is easy to set up to evaluate the
performance of the LTC3642. For a proper
measurement equipment configuration, set up
the circuit according to the diagram in Figure 2.
1. Connect the input power supply to the VIN
and GND terminals. Connect the load between
the VOUT and GND terminals. Refer to Figure 2
for the proper measurement equipment setup.
NOTE: When measuring the input or output voltage ripple, care must be taken to avoid a long
ground lead on the oscilloscope probe. Measure
the input or output voltage ripple by touching the
probe tip directly across the VIN or VOUT and GND
terminals. See the Measurement Equipment Setup diagram in Figure 1 for proper scope probe
technique. To reduce the output voltage ripple further additional capacitor of 100µF can be added in
parallel.
2. Before proceeding to operation, insert
jumper shunt XJP1 into the OFF position and
insert jumper shunt into XJP2, XJP3 or XJP4
for voltages of 1.8V, 3.3V or 5V respectively.
Set the load output current to 20 mA.
Please follow the procedure outlined below for
proper operation.
3. Apply 6V at VIN. Measure VOUT; it should
read 0V. If desired, one can measure the shutdown supply current at this point. The supply current will be about 3 µA in shutdown.
4. Turn on VOUT by changing shunt XJP1 from
the OFF position to the ON position. The out-
1
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1429A
HIGH EFFICIENCY, HIGH VOLTAGE 50MA SYNCHRONOUS STEP-DOWN
CONVERTER
put voltage should measure according to the
voltage set by the shunt jumper in XJP2, XJP3
or XJP4.
6. Vary the VOUT load current from 1mA to
50mA, and the output voltage should be within
a tolerance of ± 2.7%.
5. Vary the input voltage from 6V to 45V.
Warning - If the power for the demo board is carried in long leads, the input voltage at the part could
“ring”, which could affect the operation of the circuit or even exceed the maximum voltage rating of the
IC. To eliminate the ringing, insert an electrolytic capacitor (for instance, Panasonic part # EEU-FC2A680L,
68µF/100V) on the pads between the input power and return terminals on the bottom of the demo board.
The (greater) ESR of the electrolytic will dampen the (possible) ringing voltage due to the use of long input leads. On a normal, typical PCB, with short traces, the capacitor is not needed.
Figure 1. Measuring Input or Output Ripple
_
IIN
_
A
_
LOAD
+
V
VIN
+
+
VOUT
_
+
A
_
V
+
_
+
Figure 2. Equipment setup to test LTC3642
2
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1429A
HIGH EFFICIENCY, HIGH VOLTAGE 50MA SYNCHRONOUS STEP-DOWN
CONVERTER
3
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1429A
HIGH EFFICIENCY, HIGH VOLTAGE 50MA SYNCHRONOUS STEP-DOWN
CONVERTER
Item
Qty Reference
Part Description
REQUIRED CIRCUIT COMPONENTS
1
1
CIN
Cap., X5R 2.2uF 50V 20%
2
1
COUT
Cap., X5R 10uF 6.3V 20%
3
1
COUT1
Cap., X7R 0.1uF 16V 20%
4
1
CSS
Cap., X5R 6800pF 25V 20%
5
1
L1
Inductor, 100uH
6
1
RFB1
Res., Chip 1.47M 0.06W 1%
7
1
RFB2
Res., Chip 1.18M 0.06W 1%
8
1
R1
Res., Chip 2M 0.06W 5%
9
1
U1
I.C., Volt. Reg.
ADDITIONAL DEMO BOARD CIRCUIT COMPONENTS
1
0
CFFW (Opt)
Cap., NPO 22pF 25V 10%
2
1
CIN1
Cap., X7R 0.22uF 100V 20%
3
1
R4
Res., Chip 4.7 Ohm 0.25W 5%
4
0
R2 (Opt)
Res., Chip 715K 0.06W 1%
5
1
R3
Res/Jumper, Chip 0 Ohm 1/16W 1 AMP
6
1
RFB3
Res., Chip 475K 0.06W 1%
7
1
RFB4
Res., Chip 280K 0.06W 1%
8
0
RSET (Opt)
Res., 0402 TBD
HARDWARE FOR DEMO BOARD ONLY
1
6
E1,E2,E3,E4,E5,E6 Turret, Testpoint
2
1
JP1
Headers, 3 Pins 2mm Ctrs.
3
3
JP2,JP3,JP4
Jumper, 2pins 2mm Ctrs.
4
2
XJP1,XJP2
Shunt, 2mm Ctrs.
5
1
FAB, PRINTED CIRCUIT BOARD
6
1
STENCIL
Manufacturer / Part #
TDK C3225X5R1H225MB
TDK C3216X5R0J106M
AVX 0603YC104MAT
AVX 04023D682MAT2A
TDK VLCF5020T-101MR27
Vishay CRCW04021M47FKED
Vishay CRCW04021M18FKED
Vishay CRCW04022M00JNED
Linear Tech. Corp. LTC3642EDD
AVX 04023A220KAT2A
AVX 12061C224MAT2A
Vishay CRCW12064R70JNED
Vishay CRCW0402715KFKED
Vishay CRCW04020000Z0EA
Vishay CRCW0402475KFKED
Vishay CRCW0402280KFKED
Mill Max 2501-2-00-80-00-00-07-0
Samtec TMM-103-02-L-S
Samtec TMM-102-02-L-S
Samtec 2SN-BK-G
DEMO CIRCUIT 1429A
STENCIL
4
Similar pages