DC1424A - Demo Board

DEMONSTRATION CIRCUIT 1424A-A/B
QUICK START GUIDE
LT3581
BOOST/INVERTING DC/DC CONVERTERS
DESCRIPTION
Demonstration circuits 1424A-A and 1424A-B
feature the LT3581 in Boost/Inverting Regulator
configurations. The Boost is designed to convert a 5V to 10V input source to 12V at 900mA,
and the Inverter a 5V to 12V to -12V at 750mA.
DC1424A-A is designed to survive output short
circuit events with the external MOSFET installed at the output as default. The demo board
includes an option to install the MOSFET at the
input side. Install Q1 and R1 on the back of the
board and refer to Figure 4 for other instructions. DC1424A-B can easily be converted into
a SEPIC Converter by swapping L2 and D2
from their respective locations as shown in Figure 5. The LT3581 includes a 42V Master and
Slave switch combination with 3.3A total current
and can be used in many configurations such
as Boost, SEPIC, CUK and Flyback. It has a
2.5V to 22V operating input range, UVLO, softstart, programmable switching frequency and
many other popular features. The LT3581 is
suitable for many applications, such as Local
Bias Supplies, VFD, TFT-LCD Supplies and
Automotive Engine Control Power. The LT3581
datasheet gives a complete description of the part,
its operation and application information. The
datasheet must be read in conjunction with this
quick start guide for working on or modifying the
demo circuit 1424A.
Design files for this circuit board are
available. Call the LTC factory.
LT is a trademark of Linear Technology Corporation
PERFORMANCE SUMMARY DC1424A-A Specifications are at TA = 25°C
SYMBOL
VIN
VOUT
Efficiency
Ripple
Fs
PARAMETER FOR BOOST CONVERTER CONDITIONS
Input Supply Range
Output Voltage Accuracy
VIN = 5V to 10V, ILOAD = 900mA
VIN = 5V, ILOAD = 900mA
VIN = 5V, ILOAD = 900mA
Switching Frequency
MIN
5
11.60
TYP
12
88
100
1.2
MAX
10
12.30
UNITS
V
V
%
mV
MHz
MAX
12
-12.30
UNITS
V
V
%
mV
MHz
PERFORMANCE SUMMARY 1424A-B Specifications are at TA = 25°C
SYMBOL
VIN
VOUT
Efficiency
Ripple
Fs
PARAMETER FOR CUK CONVERTER
Input Supply Range
Output Voltage Accuracy
Switching Frequency
CONDITIONS
VIN = 5V to -12V, ILOAD = 750mA
VIN = 5V, ILOAD = 750mA
VIN = 5V, ILOAD = 750mA
MIN
5
-11.60
TYP
-11.9
81
20
1.2
1
DEMONSTRATION CIRCUIT 1424A-A/B
QUICK START GUIDE
QUICK START PROCEDURE
Demonstration circuit 1424A-A and 1424A-B
is easy to set up to evaluate the performance
of the LT3581. Refer to Figures 1 and 2 for
proper measurement equipment setup and
follow the procedure below:
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 Figure 2 for
proper scope probe technique.
1. Place jumper in the following position:
JP1 On
2. With power off, connect the input power
supply to Vin and GND.
Apply 5V to input.
Check for the proper output voltages.
NOTE. If there is no output, temporarily
disconnect the load to make sure that the
load is not set too high.
Once the proper output voltage is established,
adjust the load within the operating range and
observe the output voltage regulation, ripple
voltage, efficiency and other parameters.
2
DEMONSTRATION CIRCUIT 1424A-A/B
QUICK START GUIDE
Figure 1. DC1424A-A Proper Equipment Setup
3
DEMONSTRATION CIRCUIT 1424A-A/B
QUICK START GUIDE
Figure 2. DC1424A-B Proper Equipment Setup
Figure 3. Proper Input/Output Ripple Measurement Technique
4
DEMONSTRATION CIRCUIT 1424A-A/B
QUICK START GUIDE
Figure 4. Using Disconnect MOSFET at the Input Side
5
DEMONSTRATION CIRCUIT 1424A-A/B
QUICK START GUIDE
Figure 5. SEPIC Conversion Instructions
6
DEMONSTRATION CIRCUIT 1424A-A/B
QUICK START GUIDE
7
Similar pages