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LM5050-1: LM5050-Q1 Output reverse polarity protection

Wei-Hao Chen (TW-FAE)
Expert 3260 points
Part Number: LM5050-1


Hi Support team,

My customer wanted to use LM5050-Q1 Oring controller for battery charger application, the output of oring is connected to a battery and they need to have the reverse polarity protection for the output to prevent the battery terminal is connected wrongly.

Is it okay to move D1 and D3 from input to output to achieve this? 

Also, does it need the back-to-back MOSFET to prevent the voltage from the output because the body diode cannot block the negative voltage from output even the MOSFET is OFF.

Thank you.

Best Regards,

Wei-Hao

  • 0
    TI__Genius 16305 points
    Hi Wei-Hao,

    For output reverse polarity protection, back-back MOSFET is needed.

    Because, in the above schematic, when output reverse polarity is applied, Cin will get charged through body diode and negative voltage would show up on the input of LM5050-1. Hence you need to have MOSFET opposing this in a back-back configuration for this to work.

    Also Cout can not be electrolytic capacitor and D2 has to removed.


    Regards,
    Kari.