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ISO3086T: Can an isolated transceiver be used if the grounds are common?

Brian Pevear
Prodigy 20 points
Part Number: ISO3086T

We have a system where a contactor provides galvanic isolation between two grounds. We use an isolated RS485 transceiver to maintain communications between two controllers in this isolated state.

When the contactor is closed, the "isolated" ground will then be common to the "non-isolated" ground. Is there any degradation of performance of the isolated RS485 transceiver in this case (i.e. when GND1 and GND2 are joined together)? 

  • 0
    TI__Guru 53855 points
    Hi Brian,

    ISO3086T has two separate sections in device (Side1 & Side2) that are completely independently powered and operate independently as well. Even if the same power supply is connected to both the sides, the device would still operate as if the two supplies are different. Hence this connection is not a problem for device function. So would also be the case if the GND1 & GND2 are shorted even when they are powered from two different power supplies.

    Though device will function normal, there would not be any isolation between the sides as GND1 and GND2 are shorted. If not having isolation barrier for the situation specified (contactor closed) is okay for the application and not causing any issues, then it shouldn't be a problem for ISO3086T either. Thanks.


    Regards,
    Koteshwar Rao
  • 0 in reply to Koteshwar Rao
    Prodigy 20 points

    Excellent. Thank you for your prompt response.