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TPS25926: Back powering the device

Carlo
Expert 7715 points
Part Number: TPS25926

Hi team,


Our customer would like to use the TPS25926 with USB Power Delivery. When this eFuse is back powering, the current will flow through the MOSFET body diode and to the IN pin and then to USB-C port. Is the MOSFET will turn on when back powering is applied since the voltage at IN pin will be at least 5 Volt?

Regards,
Carlo

  • 0
    TI__Guru 57737 points

    Hi Carlo,

    TPS25926 eFuse has only one FET integrated and allows reverse current from OUT to IN when VOUT > VIN.

    In case you want reverse current blocking, please have a look at TPS25947 . This device has blocking FET integrated and supports zero reverse current from OUT to IN. 

  • 0 in reply to Praveen GD
    TI__Expert 7715 points

    Hello Praveen,


    Thank you for your reply. As you said that TPS25926 allows reverse current from OUT to IN when VOUT > VIN, could you inform which the current flows? Is it through FET body diode because internal FET is still turn off or through FET channel as a result of internal FET is turn on?


    Regards,
    Carlo

  • 0 in reply to Carlo
    TI__Guru 57737 points

    Hi Carlo,

    When the eFuse  internal FET is ON and VOUT > VIN then the reverse current will flow through the FET channel.

    If the internal FET of the eFuse is OFF due to conditions like Vin < Vuvr then if the reverse current would flow through the body diode of the FET when Vout > VIN. 

  • 0 in reply to Praveen GD
    TI__Genius 16655 points

    Hi Praveen,

    We just have a follow-up inquiry.

    There is a current sense sensor at the drain of internal FET, in normal condition (current flowing from VIN to VOUT) the current sense sensor give positive voltage feedback to internal comparator via its non-inverting input and when the voltage is more than some limit then it is indicate the over current condition occurs.

    When current flowing backward (from VOUT to VIN), is this current sensor still operating as usual?

    Thanks!

    Art

  • 0 in reply to Art Mecina
    TI__Guru 57737 points

    Hi Art,

    The current limit circuit will not work when the current flows from Vout to Vin because the body diode will not allow regulation of current in its forward direction.