DC1200A - Demo Manual

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1200
2A 100KHZ HIGH VOLTAGE BUCK CONVERTER
LT3430-1
DESCRIPTION
Demonstration circuit 1200 is a 60V, 100kHz, 2A load
current, monolithic step-down DC/DC switching converter using the LT3430-1. With its wide input voltage
range, 3A internal power switch, and thermally enhanced package, the LT3430-1 is a very versatile and
powerful IC for DC/DC converters that require compact space and a wide variety of input voltage ranges.
The constant 100kHz switching frequency allows the
input voltage to be as high as 60V for a 3.3V output
without pulse-skipping. The current-mode control
topology creates fast transient response and good
loop stability with a minimum number of external
compensation components and the use of ceramic
input and output capacitors if desired. The low resistance internal power switch (0.1Ω) and 100kHz
switching frequency give efficiencies up to 90%. The
30µA shutdown current extends battery life. The wide
input range allows step-down configurations with input voltages between 5.5V and 60V. The LT3430-1 is
synchronizable above 125kHz. Please refer to the
datasheet for details.
Demonstration Circuit 1200 is a step-down converter
using the LT3430-1. The circuit is designed for 5.560V input to 3.3V output at 2A load current for automotive, industrial, portable computers, battery chargers, and distributed power systems. This board was
designed for wide input voltage range applications
with low component count and up to 2A of load current. The low-ESR tantalum output capacitor reduces
output voltage ripple.
The LT3430/LT3430-1 datasheet is available at
www.linear.com for more details regarding LT3430-1
applications and specifications.
Design files for this circuit board are available. Call
the LTC factory.
LT is a trademark of Linear Technology Corporation
Table 1. Typical Performance Summary
PARAMETER
CONDITION
VALUE
Steady State Input Voltage Range
VOUT = 3.3V, IOUT <= 2A
5.5 – 60V
Maximum Transient Input Voltage
All Vout (customized)
60V
VOUT
IOUT <= 2A
3.3V ±3%
Maximum Output Current
2A
Typical Switching Frequency
100kHz
Efficiency
VIN = 12V, VOUT = 3.3V, IOUT = 500mA
85%
Output Voltage Ripple
VIN = 12V, VOUT = 3.3V, IOUT = 2A
25mVPK-PK
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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1200
2A 100KHZ HIGH VOLTAGE BUCK CONVERTER
QUICK START PROCEDURE
Demonstration circuit 1200 is easy to set up to evaluate the performance of the LT3430-1. Refer to Figure
1 for proper measurement equipment setup and follow the procedure below:
NOTE: Make sure that the input voltage does not exceed 60V.
NOTE: Do not hotplug the input at voltages above 24V
to prevent input overvoltage.
load to the Vout and GND terminals on the board.
4. Connect an ammeter in series with output load to
measure output current.
5. Connect a voltmeter across the Vin and GND ter-
minals to measure input voltage.
6. Connect a voltmeter across the Vout and GND ter-
minal to measure output voltage.
1. Connect the 5.5-60V input power supply to the Vin
and GND terminals on the board with the power
supply turned OFF.
2. Connect an ammeter in series with the input supply
to measure input current.
3. Connect either power resistors or an electronic
7. After all connections are made, turn on input power
and verify that the output voltage is 3.3V.
8. The synchronization and shutdown functions are
optional and their pins can be left floating (disconnected) if their functions are not being used.
Figure 1. Proper Measurement Equipment Setup
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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1200
2A 100KHZ HIGH VOLTAGE BUCK CONVERTER
100%
95%
90%
5 V IN
85%
12 V IN
80%
2 4 V IN
75%
4 8 V IN
70%
65%
60%
55%
50%
0
0.25 0.5 0.75
1
1.25 1.5 1.75
2
Figure 4. Typical VOUT ripple 12VIN 2A load
LOA D CURRENT (A )
Figure 2. Typical shutdown current versus input voltage
µ
40
35
30
25
20
15
Figure 5. Typical VOUT ripple 48VIN 2A load
10
5
0
0
10
20
30
40
50
60
INP UT VOLTA GE (V)
Figure 3. Typical shutdown current versus input voltage
3
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1200
2A 100KHZ HIGH VOLTAGE BUCK CONVERTER
4
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