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ISO7740-Q1: Allowed number of repetitions high voltage test (2500V dc 60s)

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Part Number: ISO7740-Q1

Hello,

we are using  ISO7742QDWQ1 within the electronic of our automotive high voltage pump (800V supply).

Our customer want to do a high voltage withstand test on his complete System, in what our pump is a part of.

The test applies 2500V DC for a time of max, 60sec between case/low-voltage terminals and high voltage terminals of the pump,

i.e. the ISO7742QDWQ1 will 'see' the test-voltage on its Isolation barrier and I suppose it will be stressed.

In this context  the question rose up,  how often the  ISO7742QDWQ1  allows this stress, without decline performance or lifetime Parameters.

I couldn't find anything about that in the data-sheet.

Do you have an answer on this  special  question?

Regards,

Martin

  

  • Hi Martin,

    Thank you for showing interest in ISO7742-Q1.

    The transient parameters that are guaranteed in datasheet are VISO & VIOTM both of which are defined for 60 seconds. For ISO7742-Q1 in DW package, VISO is 5kVrms and VIOTM 8kVpk. The definitions of transient parameters VISO and VIOTM state that the device is guaranteed to support the rated voltage for an accumulated time of 60 seconds over a period of device lifetime. Once the accumulated time exceeds 60 seconds at rated voltage, the device is not expected to support this voltage anymore. This means that device lifetime after VISO/VIOTM for 60 seconds is zero.

    With that said, TI devices have very high margin to what the device is rated. Please refer to the below TDDB data that indicates projected insulation lifetime of isolation barrier for the stated voltages. This plot is also provided in ISO7742 datasheet in Figure 28 (this is yet to be updated to ISO7742-Q1 datasheet).

    As indicated in the plot, the projected device lifetime for 2.5kVrms is >30 years. Please do note that the projected lifetime data is for the isolation barrier and not for the packaged device as the package has other dependencies (like creepage) to be rated for a given voltage. From the data, you can infer that ISO7742 can support multiple instances of 60 second 2.5kV DC test without impacting device performance but we will only be able to guarantee an accumulated time of 60 seconds for 5kVrms in datasheet.

    I hope that answers your question, thank you.

    Regards,
    Koteshwar Rao