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LM2677: Is input reverse polarity protection required?

Craig Javid1
Prodigy 50 points
Part Number: LM2677
Other Parts Discussed in Thread: LM2676,

I am working on a new buck design using the LM2677 with 12VDC in and 6.3VDC out at 4A.  Previous switchers like the LM2676 did require some protection against input voltage reversal but it is not clear to me that the LM2677 requires this protection.  Please clarify.

Thanks

  • 0
    TI__Mastermind 22299 points

    Hi Craig,

    Yes you must have input reverse polarity protection on the LM2677.

    The highside MOSFET has a parasitic diode from SW output to VIN.

    This is reverse bias for positive VIN but if VIN is negative then you have two diodes (from GND) that will conduct harmful reverse current.

    Hope this helps,

    -Orlando