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ISOUSB211: to pass EFT test, any design tips for ISOUSB211

Ken Zhang
Expert 3595 points
Part Number: ISOUSB211

Hi, 

   during EFT tests based on IEC 61000-4-4 with ISOUSB411, the data communication is failure in customer design. are there any design tips for ISOUSB211 to match EFT tests?

  • 0
    TI__Guru 55815 points

    Hi Ken,

    Thanks for reaching out.

    Please share the below information to understand the issue better,

    1. What is the test level that the device passed and the level it failed during customer test?
    2. What was the pass criteria? Criterion A or Criterion B?
    3. What was the length of cable used?
    4. Please share a photograph showing the EFT test setup with cable placed under the EFT clamp and PC/EUT connected on both sides.

    Since USB is low voltage communication bus, injected noise onto data lines can affect the data and interrupt communication when the noise levels become significant. We expect Criterion A pass upto 1kV and Criterion B upto 1.5kV. The best way to achieve optimum test results is to use shielded cable and suitable TVS diodes. It is also important that all the datasheet guidelines for schematic and PCB layout are also followed. Thanks.


    Regards,
    Koteshwar Rao

  • 0 in reply to Koteshwar Rao
    TI__Guru 55815 points

    Hi Ken,

    I wanted to check if you will be able to help me with the information I have requested in my post above. Thanks.


    Regards,
    Koteshwar Rao

  • 0 in reply to Koteshwar Rao
    TI__Expert 3595 points

    Koteshwar

    thanks for your consistently support.

    pls refer to the test setup in attach.

    after on-site check customer's layout, we find that the isolation creepage between side 1 to side of ISOUSB211 is < 1mm. this small creepage should not help any isolation effects. Therefore, customer will re-layout ISOUSB211 at first, then do EFT test. 

    if needs any further help, will let you know.

    EFT test setup.pdf

  • +1 in reply to Ken Zhang
    TI__Guru 55815 points

    Hi Ken,

    Thank you for sharing the update along with block diagram and test setup picture, this is very helpful. Yes, <1mm creepage could affect the EFT results. Improving creepage should help improve the results.

    I see that customer is testing their end-equipment with the enclosure removed. If possible, please ask customer to test it with the case enclosed. The EFT noise can be easily picked up when the device is exposed, so it is better to test it with the case enclosed to reflect actual use-case.

    I will go ahead and mark this closed for now. Once you have an update, you can either respond to this post or create a new one. Thanks.


    Regards,
    Koteshwar Rao

  • 0 in reply to Koteshwar Rao
    TI__Expert 3595 points

    Koteshwar,

     the new layout file is sent to you by Email. pls kindly help give your suggestions.