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ISO1500: One Master device communicates with Multiple field Salves through RS485 , how to prevent ground loop problem

wen yuanming
Prodigy 20 points
Part Number: ISO1500
Other Parts Discussed in Thread: THVD2450,

Dear TI FAE,

I am designing a system including a Master and Multiple-drop slaves communicating  with RS485, I only use a isolated RS-485 transceiver(both power and data isolated) at Master side,  all slaves side  use non-isolated THVD2450. The Master isolated side GND_485iso is not connect to all slave side GND_slave, will there some ground loop issue with this structure?  and what is the best recommendation for this kind of design? 

Thanks

Dennis

  • 0
    TI__Intellectual 1960 points

    Hi Dennis:

    Thanks for posting your question on E2E!

    RS-485 transceivers are inherently robust to operate with certain amount of ground potential differences. In fact, THVD2450 can operate up to +/-25V of ground potential difference between two RS-485 nodes. Isolated RS-485 transceiver, such as ISO1500, can increase the working voltage up to 566VDC.

    Grounding is a common question about RS-485 systems. You may refer to this E2E for more details. In addition, you may find this app brief useful.

    Regards,

    Dushmantha