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ISO7720-Q1: VIO condition of RIO(Isolation resisrance) parameters

Hidekazu Someno
Expert 5130 points
Part Number: ISO7720-Q1

Hi Team,

I would like to just confirm somethings about the VIO test conditions of RIO parameter of ISO7720QDRQ1.

Regarding RIO parameter on datasheet, It has been tested under VIO=500V. 

- What is the reason why VIO condition is set as 500V?  Does it depend on the conditions specified by any insulation standard?

- How does the RIO resistance change at the higher VIO voltage than 500v?

Regards,

H.Someno

  • 0
    TI__Genius 10075 points

    Hi,

    Yes, VIO = 500V is specified in IEC and VDE standards, for example, DIN VDE V 0884-11, for the measurement of RIO.

    RIO test is used to ensure that isolation barrier integrity is intact after high voltage stress.

    RIO should not change if you marginally increase VIO across isolation barrier but if you increase VIO too much then it can becomes a high voltage stress event itself and it can damage the isolation barrier and reduce RIO value. But at that point, it isn't a diagnostic test but a high voltage stress event. :)

    I hope this clarified your questions.

  • 0 in reply to Saleem Marwat
    TI__Expert 5130 points

    Thanks.

    I have one more question from customer about RIO spec on datasheet.

    Customer would like to know how RIO changes compared with current spec. at VIO=500V when VIO is around 1200v.

    In case of VIO=1200V,  Will RIO drop significantly?

    Do you have any comments about this?

    Regards,

    H.Someno

  • 0 in reply to Hidekazu Someno
    TI__Genius 10075 points

    RIO is resistance across isolation barrier and it should not change when VIO is increased from 500V to 1200V. The resistance will change only when there is a physical change through tracking or damage to the isolation barrier.

  • 0 in reply to Saleem Marwat
    TI__Expert 5130 points

    Hi,  

    Please advise about the following questions.

    Originally, the information that customer wanted to know was the DC insulation withstand voltage on the input side and output side in the non-energized state.

    Q1: What is this voltage for ISO7720QDRQ1?

    Q2: There is a spec of 637Vdc in the VIOWM parameter list in the data sheet. Can this be considered as the insulated DC withstand voltage in non-energized state required by the customer?   If so, we can answer this 637V as a DC insulation withstand voltage to customer's question.

    Best regards,

    H.Someno

     

  • +1 in reply to Hidekazu Someno
    TI__Genius 10075 points

    Yes, 637V DC voltage can be used as DC insulation withstand voltage. This device can easily sustain this voltage for its lifetime (> 20 years).