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ISOUSB211: ISOUSB211 Galvanic Isolation Voltage Difference

Halid CEYLAN
Prodigy 30 points
Part Number: ISOUSB211

Tool/software:

Hello,


We also use the galvanic isolated SN6505 circuit in our ISOUSB211 circuit. It is natural that there is a voltage difference in ISO GND and Digital GND measurements due to the transformer structure. Is it possible to minimize the voltage difference between ISO GND and Digital GND without damaging the galvanic isolation?


What are your recommendations?

Best Regards.

  • +1
    Guru 286180 points

    When the voltage difference already exists, then the only way to reduce it is to allow a current to flow between the two sides (i.e, with a direct connection or a resistor).

    What is the reason for the voltage difference? If you have a device at a floating potential, then a small current that flows for a limited time might be resonable (depending on what you need isolation for). But if the voltage difference is forced by some external power supply, then you cannot reduce the difference.

  • 0
    TI__Guru 54765 points

    Hi Halid,

    Welcome to TI E2E forum!

    Since GND1 and GND2 are isolated, the voltage difference between them depends on the external isolation voltage applied between them. If there is no voltage applied between them then it could read 0V just they way an open-circuit would read 0V (or like the unconnected multi-meter terminals read 0V).

    Let me know exactly why you would like to reduce this voltage and more details about your application so that I can comment better. Thanks.


    Regards,
    Koteshwar Rao

  • 0 in reply to Clemens Ladisch
    Prodigy 30 points

    Thanks for your valuable feedback.

  • 0 in reply to Koteshwar Rao
    Prodigy 30 points

    There are parts of the circuit that do not need to be isolated. I wanted to ask if we can solve it without connecting an external component (in terms of the area it will take up).


    I think we will need an extra isolator circuit again :)


    Thank you for your feedback.