LM3753_1 Datasheet, PDF (1/20 Pages) National Semiconductor (TI) – Evaluation Board evaluation board is designed to provide

LM3753/54 Evaluation
Board
National Semiconductor
Application Note 2021
Robert Sheehan, Michael Null
December 15, 2009
Introduction
The LM3753/54 evaluation board is designed to provide the
design engineer with a fully functional power converter based
solution using two LM3753 or LM3754 2-Phase Buck Con-
trollers. This evaluation board produces an output voltage of
1.2 V at 25A per phase for a total of 100A. The switching fre-
quency for the converter is set to 300 kHz per phase, for an
effective 1.2 MHz at the input and output. The gate signals for
each controller’s outputs are 180 degree out of phase, with
the two controllers having a 90 degree phase shift from each
other. The printed circuit board consists of 4 layers of FR4
material with 2 ounce copper on all layers. This application
note contains the evaluation board schematics, Bill-of-Mate-
rials (BOM) and a quick setup procedure. Refer to the
LM3753/54 datasheet for complete circuit design information.
The performance of the evaluation board is as follows:
Input Range
Output Voltage
Output Current
Switching Frequency
Load Regulation
Board Size
: 6V to 18V
: 1.2V ± 1%
: 0A to 100A
: 300 kHz
: 0.1%
: 4.2 x 5.4 x 0.063 inches
Powering and Loading
Considerations
Read this entire page prior to attempting to power the evalu-
ation board.
QUICK SETUP PROCEDURE
Step 1: Use an input power supply with at least 30A current
capability. Connect the positive output of the power supply to
the VIN terminal T1. Connect the negative output of the power
supply to the input GND terminal T2.
Step 2: Connect a load with 100A capability to the VOUT ter-
minal T3 and GND terminal T4.
Step 3: (LM3753 only) Connect a secondary power supply
to the TRACK terminal TP13 and GND terminal TP2. Set the
power supply voltage to 3.3V. Since the LM3753 is configured
such that VOUT follows the TRACK input, VOUT cannot
come up without applying a voltage to TRACK.
Step 4: Ensure that the Load Pulse switch SW1 is in the cen-
ter OFF position. Check that the current limit trimmers R18
and R26 are turned fully clockwise for maximum output cur-
rent. J1, J3, J5 and J7 should be installed, with J2, J4, J6 and
J8 open.
Step 5: Set VIN to 12 V with no load being applied. Turn on
the input power supply (followed by the secondary power
supply for the LM3753 TRACK). The output voltage should
be in regulation with a nominal value of 1.2V.
Step 6: Slowly increase the load while monitoring the output
voltage. The output voltage should remain in regulation up to
the full load current of 100A.
Step 7: Slowly vary the input voltage from 6V to 18V. The
output voltage should remain in regulation with a nominal val-
ue of 1.2V.
FIGURE 1. Basic Test Setup for the LM3753/54 Evaluation Board
30111201
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