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TPSI2140-Q1: 1500V Insulation Monitor Circuit using only TPSI2140-Q1 Components

Part Number: TPSI2140-Q1
Other Parts Discussed in Thread: TPSI2072-Q1,

Hi TI,

I am interested in an insulation monitoring solution similar to the one shown in this thread: https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1185002/tpsi2140-q1-insulation-resistance-measurement?tisearch=e2e-sitesearch&keymatch=TPSI2140-Q1#

Would it be possible to use 2x TPSI2140-Q1 components instead of the TPSI2072-Q1 shown in the diagram?

Thanks,

Bryan Grant

  • Hi Bryan,

    Thanks for reaching out on this. There is a way to utilize just 2x TPSI2140-Q1 devices for a 1500V insulation monitoring solution, however, it requires a couple other components to ensure that we do not exceed the 1200V standoff voltage rating of the device.

    To do this, you would need to add some additional resistors in parallel to the TPSI2140-Q1 devices in order to limit the maximum voltage seen at the TPSI2140-Q1 to under 1200V. The caveat with this approach is that you would have a constant leakage path due to the additional path we create with this topology.

    Let me know if this is clear.

    Thanks!

    Bryan

  • Hi Bryan,

    Thanks for the message! Thanks for this. It could work for us.

    I just want to clarify my question. I was originally thinking of this general circuit:

    Based on this diagram, I have a few questions:

    1. In the previous post, it seemed like the the TPSI2072-Q1 was used in this configuration. I assumed that the working voltage requirement could be increased in a series configuration. Is this correct?
    2. I'm trying to meet a higher transient voltage isolation (Viotm) requirement of 8000Vpk based on IEC 60664-1 for reinforced insulation. Currently, these devices are only rated to 5300Vpk. Would configuring them in series like this decrease the transient isolation voltage per component?
    3. Would this component be classified as basic or reinforced insulation?
    4. Or, could external transient protection help increase the overall transient isolation voltage?

    Thanks for the help!

    Bryan Grant

  • Hello Bryan,

    Thanks for the clarification.

    In the previous post, it seemed like the the TPSI2072-Q1 was used in this configuration. I assumed that the working voltage requirement could be increased in a series configuration. Is this correct?

    This is correct.

    I'm trying to meet a higher transient voltage isolation (Viotm) requirement of 8000Vpk based on IEC 60664-1 for reinforced insulation. Currently, these devices are only rated to 5300Vpk. Would configuring them in series like this decrease the transient isolation voltage per component?

    I don't think our voltage isolation would stack here, need to double check and get back to you here.

    Would this component be classified as basic or reinforced insulation?

    TPSI2140-Q1 is classified as basic insulation.

    Best regards,
    Tilden Chen


    Solid State Relays | Applications Engineer

  • Hello Bryan,

    I double checked with our team about stacking TPSI2140-Q1s, unfortunately we don't expect it to increase transient isolation voltage (Viotm).

    Also, looking into EN mismatch delays (e.g. if one TPSI2140-Q1 turns on before the second), if we assume worst-case that there is a 700 us delay between both TPSI2140-Q1s turning on for each EN toggle, the delayed TPSI2140-Q1 would be avalanching for 700 us. Since we rate our device for 5 minutes of lifetime avalanche, worst-case we would have ~428,000 switches before we see performance degradation (assuming the same TPSI2140-Q1 is avalanching for 700 us during each switch). Unsure about how often you wanted to perform insulation monitoring but that is something to consider.

    Best regards,
    Tilden Chen


    Solid State Relays | Applications Engineer

  • Hi Tilden,

    Thanks for the explanation! This answers my questions.

    Bryan Grant