Tool/software:
My design currently has the FLT pin tied to IN though a red LED and a 10K resistor. In normal use, this gives a suitable visual indication for under voltage, over voltage, and over current situations.
However, am looking for some clarity on this usage in a reverse polarity situation. The datasheet lists the FLT pin absolute maximum rating as -0.3V to 62V (referenced to RTN), and recommended operation as 0V to 60V (presumably referenced to GND as is not noted otherwise).
When probing the FLT pin on a test board with 18V applied in reverse polarity, I am measuring approximately -150mV referenced to RTN, but -850mV referenced to GND. Increasing the reverse polarity input voltage has negligible effect on the voltage at the FLT pin when referenced to RTN, but does have a significant impact when referenced to GND (-3V @36V and -8V @48V).
Am a bit confused that the datasheet implies different references for the recommended and maximum ratings? Am unsure how concerned I should be about this...
