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TPS272C45: max allowed reverse current

Hans
Genius 12865 points
Part Number: TPS272C45


Hello Team,

The TPS272C45D is used in a setting where VOUT > VS in some cases, which leads to an inverse current through the MOSFET body diode. There is no specification in the data sheet regarding the maximum reverse current. For example the datasheet for the TPS4H160 specifies the reverse current IR(1) and IR(2). Is it possible that you make a similar specification of the maximum reverse current for the TPS272C45D?

Thanks and Best Regards, Hans

  • 0
    TI__Genius 16390 points

    Hi Hans,

    The max reverse current during ON state will be the same as max forward current which is limited by thermal. The max reverse current during OFF state will be much lower due to high body diode drop. You can estimate by accounting for max device temp and ambient temp.

    However, features such as current limit will not work properly during a reverse current event.

    Please let me know if any other questions.

    Regards,

    Yichi

  • 0 in reply to Yichi Zhang.
    TI__Genius 12865 points

    Hi Yichi,

    if we can specify reverse current for TPS4H160 why not for TPS272C45D?

    How can we estimate the max reverse current with the thermal resistance and ambient temp? (125°C - 25°C) / 32.2°C/W = 3.1W allowed power dissipation, correct? 3.1W = Ireverse x Vdrop. As we don't know the difference between Vout and VS (VS for sure is known) we don't know the voltage drop across the body diode. So we need to know the reverse current to calculate the allowed voltage drop.#

    Let me know if I am wrong!

    Thanks and Best Regards, Hans

  • 0 in reply to Hans
    TI__Genius 16390 points

    Hi Hans,

    You are correct that we should add that information to TPS272C45 datasheet as well. We will work on that.

    The body diode drop is around 0.7V as a fixed value (the difference between VOUT and VS). You can use this information to calculate the max reverse current.

    Please let me know if you have additional questions.

    Regards,

    Yichi

  • 0 in reply to Yichi Zhang.
    TI__Genius 12865 points

    Hi Yichi, so 3.1W / 0.7V = 4.4A. This is more than the specified output current. I doubt that this is correct...

    Thanks and Best Regards, Hans

  • +1 in reply to Hans
    TI__Genius 16390 points

    Hi Hans,

    The specified 4A output is at 85 degC. If you do a fair comparison at 85 degC, then the max current is 1.77A.

    Regards,

    Yichi