- #1
Jdo300
- 554
- 5
Hello All,
I'm designing a circuit board that needs to run on a 12VDC supply and will need to supply a fair amount of power to drive a bunch of 12V relay coils, in addition to some electronics. Since I want to keep the voltage drop on the supply a small as possible, I thought about using a P-CH MOSFET to make an active diode on the input of the board to prevent damage if the user plugs the power in backwards.
Using this method, I would have the circuit setup like the attached picture, however, the limitation here is that the input voltage is limited to 20V because of the MOSFET gate. Under normal operating conditions, going over 20V should never be a problem for this particular design, but I'm curious to know if there are any clever ways to allow the reverse voltage to go above 20V without harming the gate (using zener diodes and resistors or something). I've tried to come up with a few ideas but so far nothing obvious sticks out. Does anyone know of any simple solutions to this problem that don't involve using any fancy ICs?
Thank you,
Jason O
I'm designing a circuit board that needs to run on a 12VDC supply and will need to supply a fair amount of power to drive a bunch of 12V relay coils, in addition to some electronics. Since I want to keep the voltage drop on the supply a small as possible, I thought about using a P-CH MOSFET to make an active diode on the input of the board to prevent damage if the user plugs the power in backwards.
Using this method, I would have the circuit setup like the attached picture, however, the limitation here is that the input voltage is limited to 20V because of the MOSFET gate. Under normal operating conditions, going over 20V should never be a problem for this particular design, but I'm curious to know if there are any clever ways to allow the reverse voltage to go above 20V without harming the gate (using zener diodes and resistors or something). I've tried to come up with a few ideas but so far nothing obvious sticks out. Does anyone know of any simple solutions to this problem that don't involve using any fancy ICs?
Thank you,
Jason O