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TPS2419: Reverse Current

user5883344
Prodigy 40 points
Part Number: TPS2419

Dear TI,

We are currently designing a N+1 Redundant Power Supply.

With the schematic as it is, (RSet = 35 ohm) we are able to get the power supply functioning properly when both Power Supplies are connected. However if one power supply is disconnected, there will be reverse current in the MOSFET, so the current will flow from the circuit to the Power Supply(which is undesirable). We tried to increase the value of Rset (we removed the Resistor), but the issue still remains.

Is there any issue with the design or with the components we are using?

Thank you,

José

  • 0
    TI__Genius 16305 points
    Hi Jose,

    35ohm RSET is very low and minimum recommended value of RSET is 1.5kohm and this is specified in the datasheet.
    This would allow lot of reverse current back into the disconnected supply.

    RSET value sets the Voff turn off threshold. Lets say if you program RSET to be 100kohm, Voff threshold will be -1.5mV. This is calculated based on the equation in the datasheet page number 6 equation 1. So then the reverse current would be Voff/RdsON. For a 10mohm MOSFET, reverse current would be 150mA.

    Could you please recheck with above values and let us know if you are still seeing issues?

    Regards,
    Kari.
  • 0 in reply to Karikalan Selvaraj
    TI__Genius 16305 points
    Hi Jose,

    Let us know if you have further questions here, otherwise if you think your question is answered please click on "this resolved my issue" button.

    Regards,
    Kari.