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ISO7762: Floating ground on secondary side

Liyang Du
Prodigy 160 points
Part Number: ISO7762

Hi TIers,

I used ISO7762 in a 3.3kV system, where the primary side is 3.3kv level to earth and the secondary side is floating that is no electrical connection to earth. The power supply of secondary side is from a 3.3kV isolation rating power source coming from primary side. Now I'm evaluating feasibility of the design in 10kV system, where I think ISO7762 can be used because I think the secondary side is floating so there should not be a high voltage difference of two sides. So the system can still work. Could you please tell me that if my thinking is correct or not? Thanks!

  • 0
    TI__Genius 17100 points

    Hi Liyang,

    Thank you for posting, and welcome to E2E! ISO7762 itself has sufficient creepage and clearance distances to isolate over 10kV transients per its datasheet specs. To prevent arcing across the isolation barrier or to Earth, ensure that sufficient creepage and clearance distances are maintained in between ground planes, traces, and connections in the PCB layout. If there is no connection to Earth across the isolation barrier, the ISO7762 might not be stressed to the 3.3kV or 10kV levels as you mentioned. 

    It seems that there have not been any issues so far, and if you would like to share a schematic or block diagram for review of your existing or new designs, we are glad to look them over. If even stronger isolation performance is needed in your new design, our digital isolators in "DWW-16" packages offer highest isolation ratings for our single devices or multiple of our digital isolators could be connected in series.

    I hope this answers your question. Please let us know if there is any other information we can provide.


    Thank you,
    Manuel Chavez