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ISO7741: ISO7741FEDW

Valerio Cattani
Prodigy 10 points
Part Number: ISO7741
Other Parts Discussed in Thread: ISO7740-Q1, ISO7740

Which is the isolation failure rate over lifetime of the ISO774x digital isolator?

Valerio

  • 0
    TI__Mastermind 49485 points

    Hi Valerio,

    Welcome to TI E2E forum!!

    I am sorry, could you please elaborate on your question?
    If you are looking for MTBF / FIT information for ISO7741, then you can find this information at the link below by entering full orderable part number. Thanks.

    https://www.ti.com/quality/docs/estimator.tsp


    Regards,
    Koteshwar Rao

  • 0 in reply to Koteshwar Rao
    Prodigy 10 points

    Dear Rao,

    Thanks a lot for your kind reply.

    I’m not looking for MTBF/FIT data, I’m looking for the probability that the isolator device “fail short” or with low resistance between the isolation barrier.

    Thanks

    Valerio

  • 0 in reply to Valerio Cattani
    TI__Mastermind 49485 points

    Hi Valerio,

    Thanks for the clarification.
    The isolation barrier of ISO7741 is not excepted to fail as long as the voltages applied do not exceed isolation ratings of device. If you meant to ask whether the device fails short or open after its isolation ratings are exceeded, then the below white paper is a good document that discusses this topic in detail.

    Understanding failure modes in isolators (Rev. A)

    As stated in the document, there are two modes in which a failure can occur. For failure mode 1, when the applied stress exceeds device ratings most devices will fail and the output can be either a short or an open but it will be random and unpredictable. For failure mode 2, where a local failure to one die doesn't damage the complete isolation barrier, instead the device maintains basic isolation.

    I hope this answers your question, please do let me know if anything is unclear to you. Thanks.


    Regards,
    Koteshwar Rao

  • 0 in reply to Koteshwar Rao
    Prodigy 10 points

    Hi Rao,

    Thank you for your support. Unfortunately your answer doesn’t solve my problem. I’m familiar with all the Texas Instruments documents and application notes such as :

    Digital Isolation Design Guide

    Understanding failure modes of isolators

    High-voltage reinforced isolation: definition and test methodologies

    Addressing high-voltage design challenges with reliable and affordable isolation technologies

    Enabling high voltage signal isolation quality and reliability

     

    All the previous documents provide only qualitative information, I need “quantitative” information such as:

    The failure rate (λ) for an isolator to fail short circuit is for example: 0.000196 Failures/106 Hours

    The only document that provides some figures is: ISO7740/ISO7740-Q1 Functional Safety FIT Rate. But unfortunately, no information on short circuit faults across the isolation barrier.

     

    Any help on this subject is really appreciated.

    Regards

    Valerio

  • 0 in reply to Valerio Cattani
    TI__Mastermind 49485 points

    Hi Valerio,

    Thanks for further clarification, it helps me understand your request better.

    We do not characterize our devices for a specific fail type and hence, I do not have any data to share related to the probability of isolator failing short. The failure information that we have is for overall failure rate and that's covered by MTBF / FIT. The functional safety document that are referring to is the document that provides more details on failures along its distribution across components and functional blocks. But all of this is still focused on overall failure and not specific to isolation barrier failing short.

    I believe the failure related information that we provide is a standard industry practice and I am sorry that I do not have quantitative data related to isolation fail short. Please feel free to let me know if I can help you with anything else, thanks.


    Regards,
    Koteshwar Rao