I have such a reverse polarity protection circuit for the power supply:
The MOSFET used has a maximum VGS of 10 V, so that's why there's a Zener diode of 7.5 V.
But what happens if I connect, let's say, 12 V? I don't fully understand how this Zener diode is working.
- It will start to conduct from 7.5 V.
- So from 12 V it will "conduct 4.5 V" to the gate.
- So the voltage on the gate relatively to the ground will be +4.5 V.
- But the voltage on the gate relatively to the source (VGS) will be -7.5 V (4.5 V – 12 V).
- This MOSFET needs around -2 V to start to conduct. It gets -7.5 V, so is that why it's working?
Am I correct with this? Do I understand this properly?