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TRF37A73: PWDN PIN

user5163865
Genius 4120 points

Part Number: TRF37A73

Hi,


Q. Could you tell me the resistance value and tolerance of the internal pull-down resistor on the PWDN pin?

An NPN transistor is connected externally to switch between Hi and Lo.
However, the current design is 1.95V at Hi.

The specifications require 2V or more, so the pull-up resistor value (R525) must be considered.

Best regards,

Hiroshi

  • 0
    Guru 140200 points

    Hi Hiroshi,

    It's a bit difficult to determine the pull-down resistance from the datasheet specifications because the input current can show big manufacturing tolerances. But I think R525 = 2k2 is a good choice.

    Kai

  • 0
    TI__Expert 4830 points

    Thanks for your support Kai.

    Hi Hiroshi,

       As Kai said 2.2K is good choice.

       There is a internal pulldown resistor to GND on EN pin, From data sheet, R_pulldown =  (VIH-VIL) / (IIH-IIL) = ~70k.(Note this is typical)

    So ideally,    3.3 * (70k / (R525 + 70k)) > 2V   ==> R525 < ~45k

    But considering the manufacturing tolerances, we internal pulldown can vary.

    So I would put anything less than 10k to be on safer side.

    Regards,

    Hruday

  • 0 in reply to Hruday Kumar Mudireddy
    Genius 4120 points

    Hi Kai-san, Hruday-san,

    I'm sorry for late reply.

    We propose 2.2k to the customer.

    Thanks a lot.

    Best regards,

    Hiroshi