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Frame vs Can ground in a Canbus unit

Andy Warne
Intellectual 615 points

I am currently designing a unit to be mounted in a car. It has a Canbus interface and controls external devices. I am unsure what to do regarding the two grounds namely the supply ground (which will be the car body) and Canbus ground.

The options I can think of are:

Dont connect Canbus ground at all to the unit, based on the fact Canbus can deal with a large ground offset

or

Connect the 2 grounds together in the unit (seems unwise)

or

Connect the Canbus ground via a resistor, and maybe a capacitor to the frame ground.

or

Run the entire unit via Canbus ground. There are external high-current devices connected though so this seems unwise.

Any feedback welcome

  • 0
    TI__Mastermind 20590 points

    In automotive the CAN bus is almost always referenced to Chassis (Frame).  CAN was designed for automotive and has a wide common mode operating range to easily handle the few volts of ground shift in a car across the chassis (frame).  IF the vehicle has an electrical wiring harness to "GND" or chassis then this should also be used.

     

    -- Scott