battpower
New Member
Hi there,
I have a circuit where I need to operate a solenoid on a truck from a PIC microcontroller. The electrical environment on a truck is very noisy with the alternator having various loads (such as lights, air con etc) being switched on and off that can cause load dumps.
One side of the solenoid is permanently connected to +12v, and the other side needs to be switched to ground to operate it. I want to use a logic level MOSFET to pull it to ground. Is it a bad idea to drive the FET directly from the PIC, or should I use some form of isolation such as an optocoupler between PIC and FET? I'm concerned that the truck ground may be noisy and could affect my digital circuit. Would a relay be a better idea and not use a FET at all? I guess for true isolation I would need to use a DC-DC converter for the supply as well since it is powered by the truck +12v. ie a transformer isolated DC-DC converter.
This leads me to main main question; what situations is electrical isolation required? Is it just good practice, or are there specific conditions where isolation is mandatory? Apologies if this is a bit vauge.
Thanks
I have a circuit where I need to operate a solenoid on a truck from a PIC microcontroller. The electrical environment on a truck is very noisy with the alternator having various loads (such as lights, air con etc) being switched on and off that can cause load dumps.
One side of the solenoid is permanently connected to +12v, and the other side needs to be switched to ground to operate it. I want to use a logic level MOSFET to pull it to ground. Is it a bad idea to drive the FET directly from the PIC, or should I use some form of isolation such as an optocoupler between PIC and FET? I'm concerned that the truck ground may be noisy and could affect my digital circuit. Would a relay be a better idea and not use a FET at all? I guess for true isolation I would need to use a DC-DC converter for the supply as well since it is powered by the truck +12v. ie a transformer isolated DC-DC converter.
This leads me to main main question; what situations is electrical isolation required? Is it just good practice, or are there specific conditions where isolation is mandatory? Apologies if this is a bit vauge.
Thanks