Tool/software:
Hello,
I tried to use a simple NMOS reverse polarity protection in my project using the CSD18540Q5B, because I had that at hand. The schematic of the reverse polarity protection can be seen below. According to SLVA835A, this should work as a reverse polarity protection.
The circuit consists of a µController that switches an external electromagnet on and off. The relevant circuitry can be seen below.
Unfortunately, I do not have info on what actually happened to the circuitry, but it is driven with a 12V car battery and the polarity can be reversed (hence the protection). If the user had connected a 24V battery, D9 should be damaged, but this component is fine. D6, D7 and D1 are charred and the copper in the high current path of the PCB disintegrated so there must have been a lot of current flowing. The only reason I can think of how this happened is the reverse polarity protection not working.
Does anybody have a hint on why it did not work?
Kind regards,
Stefan
