To capture the device FET_GOOD pin behavior while
starting up with the external FET short:
- Connect a wire between TP1 and TP2 to emaulate
the FET short behavior.
- Set the input supply voltage VIN to 12 V and
current limit of 5 A.
- While testing with LM74704-Q1, verify the jumper
J5 is populated which connects the on board generated pull-up voltage to
FET_GOOD signal.
- For testing with external
pull-up voltage, de-populate J5 jumper and apply external pull-up
voltage to TP3 (FET_GOOD).
- While testing with LM74703-Q1, verify the jumper
J5 is de-populated as the LM74703-Q1 has push-pull output of FET_GOOD and does
not require an external pull-up voltage.
- Turn ON the power supply.
- Observe the start-up profile of VIN, VOUT, GATE
and FET_GOOD.
Figure 3-4 shows startup with FET short behavior of LM74704-Q1.
Figure 3-5 shows startup with FET short behavior of LM74703-Q1.