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ISO7730-Q1: Working voltage: 800V (d/s) vs. 400V (CSA)

Martin Seeger
Expert 5381 points
Part Number: ISO7730-Q1

Dear team,

I think the title gives already some hint what the question is about:

The customer intends to use the ISO7730-Q1 in the DW package option, however it is not clear what the working voltage is:

  • The data sheet states in section 7.7 Safety-Related Certifications that the device has a working voltage of 800 VRMS for the DW-16 package
  • The CSA document however specs 400VRMS for the device in reinforced isolation spec (item 4).

Do we miss a point?

Thanks and best regards
Martin

  • 0
    TI__Genius 17100 points

    Hi Martin,

    Thank you for posting to E2E!

    ISO7730-Q1 is rated for 2121Vpk/VDC maximum working isolation voltages per its datasheet Insulation Specifications in section 7.6. This is the value TI guarantees for the isolation barrier's lifetime, per our TDDB test data.


    Please let me know if you or our customer have additional questions.


    Thank you for your time,
    Manuel Chavez


    PSA: This response has been edited and a follow up is posted for accuracy below

  • 0 in reply to Manuel Chavez
    TI__Genius 17100 points

    Hi Martin, all,

    The CSA certificate shows 400V reinforced isolation qualification because CSA gives a rating assuming a mold compound - or package material - made of a certain material group (material group III):



    Our isolators are made of materials from material group I, a material group with stronger resistance to arcing given the same creepage distance, so CSA allows for us to increase the reinforced rating to 800V as shown in our datasheet:



    Please let us know if you have additional questions.


    Thank you,
    Manuel Chavez

  • 0 in reply to Manuel Chavez
    TI__Expert 5381 points

    Hello Manuel,

    thanks for your answer. This caused some confusion - please find below the feedback:

    Our design needs to comply to reinforced insulation 600V according to IEC 62368-1 (CB report is required).

    Is ISO7730-Q1-DB suitable for approval according to these requirements? Which evidence can be used to show this to the notified body?

    Why is material group III used in the CSA report instead of the actual material group of the component (I)?

    Can you please explain the technical reason behind this? That would help us to understand the limitations / risks for certification when choosing this component.

    It is confusing to us that the datasheet states that the product is CSA certified according to IEC 62368-1 reinforced 800Vrms, while the actual CSA report states reinforced 400Vrms. Based on the statement in the datasheet we also expect that a CSA report is available that shows compliance to reinforced 800Vrms. Can you explain this? We would expect at least a note with some additional information.

    Thanks and best regards
    Martin

  • 0 in reply to Martin Seeger
    TI__Genius 17100 points

    Hi Martin,

    I understand. Please allow me to discuss this the larger Isolation team and gather information for you and our customer.

    Please expect my response in the next week.


    Thank you,
    Manuel Chavez

  • 0 in reply to Manuel Chavez
    TI__Genius 17100 points

    Hi Martin,

    The CSA Group provides ratings for Material Group III on certificates to keep all certified devices on the same level. On the ISO7730-Q1 certificate, there is a note that this family of devices meets Material Group 1:



    Each CSA end equipment standard, like IEC 62368-1, has tables to show how creepage distance correlates to working voltages. According to this standard, reinforced ratings are found on the table by dividing a device's creepage distance by 2:




    Since ISO77xx devices in DW packages have creepage/clearance distances of 8mm, the reinforced rating in the certificate is found by using half of the creepage distance (4mm), and for Material Group 3 devices of this distance, the reinforced rating is 400V:



    Since the device is composed of Material Group 1 packaging, the appropriate rating is found under Material Group 1 column for the same creepage distance, which is 800V:



    So per IEC 62368-1, ISO7730-Q1 and related devices are rated for up to 800V reinforced insulation. More details can be found in Section 5.4.3, "Creepage distances" of the 3rd edition of this standard. Please let me know if there is additional information I can provide for you or our customer.


    Thank you,
    Manuel Chavez

  • 0 in reply to Manuel Chavez
    TI__Expert 5381 points

    Hello Manuel,

    thanks a lot for the answer.

    Quick question: In the e-mail notification I saw that there were placeholders/thumbnails for images but here on E2E I only see the paragraphs with bigger gabs. Could you please try to add them (again)?

    Thanks and best regards
    Martin

  • 0 in reply to Martin Seeger
    TI__Genius 17100 points

    Hi Martin,

    You're welcome! Thank you for notifying me of this; I apologize for the error. Below is the original answer with images re-attached:


    The CSA Group provides ratings for Material Group III on certificates to keep all certified devices on the same level. On the ISO7730-Q1 certificate, there is a note that this family of devices meets Material Group 1:



    Each CSA end equipment standard, like IEC 62368-1, has tables to show how creepage distance correlates to working voltages. According to this standard, reinforced ratings are found on the table by dividing a device's creepage distance by 2:



    Since ISO77xx devices in DW packages have creepage/clearance distances of 8mm, the reinforced rating in the certificate is found by using half of the creepage distance (4mm), and for Material Group 3 devices of this distance, the reinforced rating is 400V:



    Since the device is composed of Material Group 1 packaging, the appropriate rating is found under Material Group 1 column for the same creepage distance, which is 800V:



    So per IEC 62368-1, ISO7730-Q1 and related devices are rated for up to 800V reinforced insulation. More details can be found in Section 5.4.3, "Creepage distances" of the 3rd edition of this standard. Please let me know if there is additional information I can provide for you or our customer.


    Respectfully,
    Manuel Chavez

  • 0 in reply to Manuel Chavez
    TI__Expert 5381 points

    Hi Manuel,

    thanks a lot for reposting the answer.

    This answered the question and we can close the thread.

    Thanks for the support
    Best Regards
    Martin