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TPS22910A Full time reverse current protection at Vin=0V condition

K. Sasaki14
Guru 10200 points
Other Parts Discussed in Thread: TPS22910A

Can TPS22910A prevent reverse current when Vin is 0V? I think it is possible because the FET body diode is disengaged. Is my idea correct?

Best Regards,

Kohei Sasaki

  • 0
    TI__Genius 15740 points

    Hi Kohei-san,

    The TPS22910A does have reverse current protection when VIN = 0V.  However, the device needs to be powered on before reverse current protection is enabled.  Although VOUT can power the device, there will be a slight delay before the device is powered and reverse current protection is enabled.

    Assuming that the enable pin is pulled high (device is disabled), then when VOUT comes up, reverse current flow will be allowed until the device is powered on and reverse current is prevented.

     

    Regards,

    Alek Kaknevicius

  • 0 in reply to Aleksandras_Kaknevicius
    Guru 10200 points

    Alek-san,

    Thank you for your answer.

    Our customer condition is Vin is 0V and Vout is 3.3V. In this case, my understanding is the following, is this correct?

    The reverse current flow during Vout rises up until device power on, and Vin rise up depend on reverse current, is this device power on point when Vout  is about 2V (Vin UVLO plus body diode VF)? Once after the device has been activated, reverse current protection becomes enable, and Vin becomes 0V, however TPS22910A prevents reverse current even when Vin is 0V.

     

    When the difference voltage between Vout and Vin is lower VRCP threshold, does reverse current keep fowing?

     

    Best Regards,

    Kohei Sasaki

  • 0 in reply to K. Sasaki14
    TI__Genius 15740 points

    Hi Kohei-san,

    Your understanding is correct.  To give you a better idea of the behavior, I took the following scope shot of the TPS22910A:

    With no load on VIN, the pulse on VOUT causes VIN to follow.  The reverse current across the device peaks at about 20mA and only lasts about 50ns.  Here is a zoomed out scope shot showing the behavior of VIN over time:

    I then went ahead and added a 200mA load on VIN.

    In this scope shot, the peak reverse current is about 30mA and lasts about 400ns.  However, VIN gets pulled down very quickly.  Here is a zoomed out scope shot showing the behavior of VIN over time:

    Let me know if these scope shots answer your questions.

     

    Regards,

    Alek Kaknevicius