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ISO7842: General Isolation

RJ
Intellectual 2550 points
Part Number: ISO7842

Hi Team,

Design question: The specific problem I'm looking at is isolating a high voltage (~4kV), high-ish frequency (~1MHz) signal from some low voltage digital circuitry. The ISO series looks nice, particularly the ISO7842FDWW, since it also appears to meet the 12mm 60601 creepage requirement at 4kV. 

My issue is that, as capacitively isolated systems, I imagine that they're not suitable for providing the needed isolation against high frequency AC. Is that understanding correct? If so, do we have any magnetic isolation ICs that could perform similarly and maintain the necessary creepage distance?

Regards,

RJ

  • 0
    TI__Genius 17100 points

    Hi RJ,

    Thank you for posting to E2E! The capacitive isolation barrier that TI's isolation devices use is capable of isolating both DC and digital AC signals since there are modulation circuits within our isolation devices that transmit the HIGH and LOW signal levels from DC to up to 150Mbps (75MHz) across the barrier, depending on which isolation device is used. 

    ISO7842 can transmit digital AC signals of up to 100Mbps speeds (50MHz), as shown in its datasheet below, so it does seem like the DWW package version of the ISO7842F is a suitable fit for your use case. Please let me know if you have any additional questions.




    Thank you,
    Manuel Chavez

  • 0 in reply to Manuel Chavez
    TI__Genius 17100 points

    Hi RJ,

    I apologize in case I misunderstood your requirements. TI's capacitive isolation technology is meant to isolate unwanted DC and AC voltages and currents, so it is robust against high-voltage stresses in AC conditions.

    Although we don't have data on the capacitive isolation barrier's performance up to 1MHz, the document linked here includes data showing capacitive isolation performs better than magnetic isolation in against AC voltage stresses.

    Please let us know if this information and the information in my previous response is helpful.


    Thank you,
    Manuel Chavez