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ISO7721: Impact on EMI/ EMC Qual Tests due to increase in data rate from 1 to 100MBPS for Digital Isolator

Azhar
Prodigy 110 points
Part Number: ISO7721

TI's Digital Isolator P/N# ISO7221AQDRQ1 has 1 MBPS Data rate and P/N# ISO7721QDRQ1 has 100MBPS Data rate, as the data rate is high for P/N# ISO7721QDRQ1 what will be its impact for Automotive Grade EMC STD Qualification Testing keeping same PCB layout over earlier P/N# ISO7221AQDRQ1.

  • 0
    TI__Mastermind 49345 points

    Hi Azhar,

    Thanks for your interest in ISO7721-Q1.

    This is a very broad question, it would be best if you can let us know if is any particular EMC test (one or more) that you like us to refer to while answering this question?

    Assuming the question is associated with radiation emissions as per CISPR 25 or per other automotive OEM specific standards, the device ISO7721 doesn't have anything internally that causes any issues in meeting the emissions standards. Although, it is important to note that the charging and discharging currents of the parasitic input capacitors from output of one digital device (like MCU) to input of another (like digital isolator) are going to increase in frequency and amplitude with the increase in datarate. This could cause a small increase in radiation levels if the peak currents are not limited but depends largely on how an end product is tested.

    If you can incorporate a series resistance between all the output and input connection and adjust the value to limit the peak charging current without limiting your timing performance then that would help address this concern. This can also be further adjusted, if needed, during the radiated emissions testing.

    Apart from this, I do not believe there is any other EMC test that gets worse due to increase in datarate. Let me know if you have any other questions, thanks.

    Regards,
    Koteshwar Rao