This question already has an answer here:
- Reverse polarity protection 1 answer
I've seen that circuit topology used, for example, here, but I'm not convinced that schematic is accurate (maybe you can comment). The way I see it, I can either connect the Drain-pin to the Input Voltage, or the Source-pin to the Input Voltage. Does it matter which way I connect the P-channel MOSFET, or is the protection symmetric about the drain-source channel and all that matters is that the D-S channel is in series with the input voltage?