I am developing a PCB to control turning on various fans and electric motors. The control circuitry uses an ARM processor and via a CAN bus is sent signals from a main controller to turn devices on and off. Power for the processor and control circuit is fed from a 5 volt supply from the main controller via a cable. The 5 volt and ground are 26 gauge.
The PCB uses P-channel mosfet to switch the devices. The fets are fed from a 6 gauge battery cable connected to the PCB.
I assume I will need some Transient Voltage Suppressors on the mosfet drains to handle back EMF when the mosfet is turned off and if I want to be able to soft start the motors via PWM.
Question is will I need a separate ground to allow Back EMF directly to chassis ground instead of back through 26 gauge ground wire? I assume it would be best to have a separate ground on the PCB that only the TVS is attached to so that it does not cause a ground loop with the rest of the system?
The PCB uses P-channel mosfet to switch the devices. The fets are fed from a 6 gauge battery cable connected to the PCB.
I assume I will need some Transient Voltage Suppressors on the mosfet drains to handle back EMF when the mosfet is turned off and if I want to be able to soft start the motors via PWM.
Question is will I need a separate ground to allow Back EMF directly to chassis ground instead of back through 26 gauge ground wire? I assume it would be best to have a separate ground on the PCB that only the TVS is attached to so that it does not cause a ground loop with the rest of the system?