TRF37A73: PWDN PIN

user5163865

Genius 3425 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

over 1 year ago

0 kai klaas69 over 1 year ago

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 Hruday Kumar Mudireddy over 1 year ago

TI__Intellectual 2800 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 user5163865 over 1 year ago in reply to Hruday Kumar Mudireddy

Genius 3425 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

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TRF37A73: PWDN PIN