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SN65HVD72: Different ground

Jamie Tseng
Intellectual 2405 points
Part Number: SN65HVD72
Other Parts Discussed in Thread: THVD1450

Hi Team,

May I know if SN65HVD72 work if primary and secondary are different ground?

Is there anything should be noticed while designing?

Thanks and best regards,

Jamie

  • 0
    TI__Guru 62920 points

    Jamie,

    This is OK in some cases.  It depends on how large the difference in voltage is between the two local ground reference potentials.  If this is within a few volts then the RS-485 communication should work normally.  (RS-485 transceivers are typically specified to meet a -7 V to +12 V "common mode" range in order to account for minor grounding differences.  Some devices, like THVD1450, exceed this rating and allow for larger differences.)  If the potential difference is very large, though, you may want to use isolation to allow for shared ground connections without introducing a ground loop.  You can reference Section 11 of this app note for further info:

    http://www.ti.com/lit/an/slla272c/slla272c.pdf

    Please let me know if you have any questions.

    Regards,
    Max