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ISO1050: How to handle isolated GND as a system

cafain
Mastermind 6505 points
Part Number: ISO1050

Tool/software:

HI, Staff

How do I configure the power ground for a CAN isolator?

Regarding the power supply configuration of the ISO1050DUBR and ISO1412DW currently in use, I think that ideally, both the power supply and GND on the primary and secondary sides would be isolated.
Ultimately, GND1 and GND2 will be connected to the system GND (SG) and frame GND (FG), but in that case, it is possible that the FG for both the primary and secondary power supplies will be common.
（GND1＝GND2＝FG)

Is there a problem with this connection? Or is there another way?
regards
cafain

  • 0
    Guru 278840 points

    I doubt that GND2 should be connected to anything but the cable's ground line.

    What is the overall architecture? Do all nodes use isolated transceivers (so that the CAN bus is floating), or is there one node that forces the bus ground to be its own ground?

  • +1 in reply to Clemens Ladisch
    TI__Mastermind 21035 points

    Hello Cafain, 

    As you mentioned, ideally, the primary and secondary sides would be isolated. For full isolation performance GND1 and GND2 should have no common connections. Most CAN systems have the primary side (GND1) MCU ground connected to chassis/frame ground over some resistance or capacitance. The secondary side ground (GND2) is not connected to FG and operated independently on the isolated ground.

    I hope this helps. If you have followed up questions, please respond to Clemens questions with a block diagram of your application. 

    Best,
    Andrew