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ISO7740: Insulation Lifetime Projection Data - Expalnation for changes in different datasheet revisions

Michael
Prodigy 30 points
Part Number: ISO7740

Tool/software:

I did a comparison for different datasheet revisions. But I don´t understand the changes from revision to revision.

Please can you explain me the changes, why the values are different, are the values similare/compareable and what the impact to our existing designs could be.

Thank you for your answer!

Revision Comparison


1) sllsep4g (our origin) --> sllsep4h

2) sllsep4h --> sllsep4i

2) sllsep4i --> sllsep4j (latest revision) 

  • 0
    TI__Genius 17295 points

    Hi Michael,

    Thanks for reaching out and sorry for the confusion.

    The main reason of this change is due to the change in standards and requirements. Please see the revision history from sllsep4h. The datasheets were recently updated and therefore does not include all of the revision history, I see how this can be confusing as well.

    Regards,
    Aaditya V

  • 0 in reply to Aaditya V.
    Prodigy 30 points

    Hi Aaditya,

    thank you for your fast answer. The chang from revision G to revision H is ok for me. 
    But I dont understand the change from revision H to revision I.

    Please can you check this change and ask my questions for explaination of the changes (rev H to rev I), why the values are different, are the values similare/compareable and what the impact to our existing designs could be.

    1) Ther is no information in the revision history

    2) Values are totaly different

    Revision H Revision I
    Years (max) 254 54
    Years TDDB 169 36
    Time to Fail operationg(sec) ~7E9 1E9
    Time to Fail VDE safety (sec) ~1E10 ~2E9

    Revision H

    Revision I

  • 0 in reply to Michael
    TI__Genius 17295 points

    Hi Michael, 

    The reason for all three document revision changes in regards to the TDDB graph are the same. The lifetime margins and insulation lifetime parameters were changed and updated in accordance to the newer IEC standards (IEC60747-17, VDE0884-17).

    Due to this standards change, the TDDB graph had to be changed, along with updated margins and lifetime. All newly updated datasheets for isolation devices are being updated to this new standard.

    Regards,
    Aaditya V

  • 0 in reply to Aaditya V.
    Prodigy 30 points

    Ok. Now I understand why the values and the diagram are changed.

    But this is not the answer to the other questiongs:

    - are the new values similare/compareable

    - are the new values better or worse

    - what the impact to our existing designs could be (design is done with old values, eg. TBBD: 169 yeas to now 36 yeas --> 133 yeas difference!)

  • 0 in reply to Michael
    TI__Genius 17295 points

    Hi Michael,

    Thanks for the clarification on your questions.

    The new values are not necessarily better or worse than the previous numbers. Since the margin changed from 87.5% to 50%, the lifetime years also changed. Since the device itself did not change, there is no system impact in terms of the functionality or performance of the device. 

    Regards,
    Aaditya V