- Set the input power supply
voltage to 12 V. Adjust the input supply current limit level to 10 A to protect
from any unanticipated shorts.
- Turn the input power supply off.
Connect the input supply positive terminal to the VIN terminal and the input
supply ground terminal to the GND IN terminal.
- Turn the output electronic load
off. Connect the electronic load positive terminal to the VOUT terminal and the
ground terminal to the GND OUT terminal of the LM27402 evaluation board.
- Turn the input supply on. The
part will self enable and the output voltage should be 1.5 V. Slowly increase
the load current to 20 A. The input voltage can now be adjusted as well.
CAUTION: If the input voltage
is below 5 V, the internal LDO will be in a drop out state. The output of the LDO
provides the driving voltage across the gates of the MOSFETs. If the voltage at VDD
decreases enough, the efficiency can suffer if the MOSFETs are not fully enhanced in
the on-state. The output should maintain regulation.