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  • Case ID: 282636
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Max value of external pull-up resistor

Graeme Parker

After reading this  https://devzone.nordicsemi.com/f/nordic-q-a/3830/what-is-the-value-of-the-gpio-pull-up-and-pull-down-resistor

and seeing that the internal pull-up is a relatively low value, what is the max resistance you can reliably use for an external pull-up?

The scenario is a push button which can be pressed indefinitely, thus a current draw using the internal pull-up will have an impact on battery life.

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    Not specified directly, though 470k works well. Another option if just wanting to read the switch and not use as a external wakeup is to just enable the internal pull-up prior to a switch read, then disable the pull-up. A (say) 1uSec pull-up-enabled duration every 10mSecs makes the 14k pull-up look like 14M or 200nA at 3 volts. Every 100mSec read even better at 20nA battery drain.

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    Not specified directly, though 470k works well. Another option if just wanting to read the switch and not use as a external wakeup is to just enable the internal pull-up prior to a switch read, then disable the pull-up. A (say) 1uSec pull-up-enabled duration every 10mSecs makes the 14k pull-up look like 14M or 200nA at 3 volts. Every 100mSec read even better at 20nA battery drain.

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