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ISO7721: Minimum Speed of Digital Isolator Family

Dave Kearney
Prodigy 85 points
Part Number: ISO7721

Hi, trying to confirm that running the above isolator or one of that family will run OK at 50Hz. Datasheet seems to suggest it will but wanted to confirm. What sort of series capacitance is implemented in the capacitive isolation?

Many Thanks,

Dave

  • 0
    TI__Mastermind 19890 points

    Hello Dave,

    Thank you for your question. Yes, the ISO7721 or any isolator from the same family can support a data rate of 50Hz. Could you clarify what information you are looking for regarding the isolators capacitive isolation? Our isolators use a logic input and output buffer separated by a double capacitive silicon dioxide insulation barrier. 

    Regards,
    Darrah

  • 0 in reply to Darrah Merillat
    Prodigy 85 points

    Thanks for the reply Darrah, good to have confirmation that I should not see any issues down at 50Hz. I'm just asking about the capacitive isolation because the 'series capacitor' which makes up your insulation barrier will obviously have a certain bandwidth below which it does not function well to transfer data - am wondering what the capacitance of this layer is and what the minimum practical speed would be?.

    Many Thanks for your support,

    Dave

  • +1 in reply to Dave Kearney
    TI__Mastermind 19890 points

    Hi Dave,

    Thanks for clarifying. The ISO7721 has a barrier capacitance of ~0.5pF. There is no minimum data rate limit for the ISO7721 or any isolator from the same family. You should not have any issues using a data rate of 50Hz or lower. Are you planning to use a lower data rate, or are you having any issues with a lower data rate?

    Regards,
    Darrah

  • 0 in reply to Darrah Merillat
    Prodigy 85 points

    Thanks Darrah, no no issues, just wanted to be confident before order some evaluation samples. Many thanks for the support. Cheers, Dave

  • 0 in reply to Dave Kearney
    TI__Mastermind 19890 points

    Hi Dave,

    Glad to hear you are not facing any issues. I'll go ahead and mark this thread as closed then, but if you need any support in the future, please feel free to make a new post.