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LM7480-Q1: Ideal diode controller for 3.3V output

Scott Streng
Prodigy 40 points
Part Number: LM7480-Q1
Other Parts Discussed in Thread: LM7480,

Tool/software:

Can a LM7480-Q1 be used on a 3.3V output circuit, as the VS > 3V for operation?   As the 3.3V output would fall in a current limit situation, would supplying the VS pin form an external housekeeping source be valid, or does this cause issues with the charge pump circuitry.  With an eternal VS supply, the VS > Vin (pin A)?  It looks like this can be done, as page of the datasheet, shows a zener generated supply in the figure at the lower right "Ideal Diode with 200-V Load Dump Protection".  In this particular instance VS < Vin.  I am not interested in the LM7480 going into UVLO.  I would prefer to have the 3.3V supply fold-back and the diode controller follow along, behaving like a real diode.

  • 0
    TI__Mastermind 46170 points

    Hi Scott,

    I think you are referring to this. This zener is present to keep VS <60V when VIN is > 60V. Since the recommended operating voltage is ~60V. This is a special use case to pass 200V unsuppressed load dump with a 70V rated controller.

    We cannot really supply an external VS.

    Regards,

    Shiven Dhir