3 Powering and Loading Considerations
Read this entire page prior to attempting to power the evaluation board.
3.1 Quick Start Procedure
1. Set the bench power supply current limit to 2 A. Set the power supply voltage to 12 V. Turn off the power
supply output. Connect the power supply to the LM27342 demo board. Positive connection to V
IN
and
negative connection to GND.
2. Connect a load, as high as 2 A, to the V
OUT
terminal. Positive connection to V
OUT
and negative connection to
GND.
3. Connect a signal generator to provide a synchronization signal to the SYNC terminal. Positive connection to
SYNC and negative connection to GND.
4. The EN pin should be left open for normal operation.
5. Turn on the bench power supply with no load applied to the LM27342. V
OUT
should be in regulation with a
nominal 3.3-V output.
6. Slowly increase the load while monitoring the output voltage, V
OUT
should remain in regulation with a
nominal 3.3-V output as the load is increased up to 2 A.
7. Slowly sweep the input voltage from 5 V to 20 V and back to 12 V, V
OUT
should remain in regulation with a
nominal 3.3-V output.
8. Turn on the signal generator, and synchronize the LM27342 to a 3.3-V square wave at 1 MHz. V
OUT
should
remain in regulation with a nominal 3.3-V output. Monitor SYNC and SW to observe the synchronization
behavior.
3.2 Starting Up
The EN pin is tied to V
IN
to simplify start up. The pullup resistor allows the power supply design engineer to
toggle EN independently, if desired, and observe the start-up behavior of the LM27342.
3.3 Overcurrent Protection
The evaluation board is configured with overcurrent protection. The inductor current is limited to 4.0 A
(maximum).
3.4 Synchronization
A SYNC pin has been provided on the evaluation board. This pin can be used to synchronize the regulator to
an external clock or multiple evaluation boards can be synchronized together by connecting their SYNC pins
together. Refer to the LM27342 data sheet for complete information
3.5 Adjusting the Output Voltage
The output voltage is set using the following equation where R2 is connected between the FB pin and GND, and
R1 is connected between V
OUT
and FB.
(1)
Adjusting the output voltage will affect the performance of the LM27342. In addition, output capacitors might not
be rated for the new output voltage. Refer to the LM27342 data sheet for more information.
Powering and Loading Considerations
4
LM27341 Step-Down Converter Evaluation Module User's Guide
SNVA381B – NOVEMBER 2008 – REVISED DECEMBER 2021
Copyright © 2021 Texas Instruments Incorporated
