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UCC27712: Input Pull down resistor value Consult

Rebecca Li
Prodigy 490 points
Part Number: UCC27712

Hi team,

May I ask what the value of the input pull-down resistor of HI/LI pin shown in the internal block diagram of UCC27712?

Customer applied a 10kohm to GND each outside HI/LI input pin. I saw our reference design and schematic did not suggest this resistor. Would it influences the output signal of UCC27712?

Thanks.

  • 0
    TI__Genius 11770 points

    Hello Rebecca,

    I looked at the data and it seems that the input current at 5V is about 13uA at room temp. This means the pulldown resistance is roughly 400kΩ. It also varies a lot based on temperature; you can see this in this spec of the datasheet:

    INH can vary a lot over temperature.

    Adding an external resistor will not make much difference. The main difference is that it will require more current to keep IN biased high; something like 500uA instead of roughly 13uA. That probably won't make a difference for most controllers.

    Thanks,

    Alex M.