nRF52820 input resistance

[lengci]

Dear support team,

Could you clarify input resistance in float of the nRF52820 COMP? We need a high-precision resistance to calculate.

[ketiljo]

Are you thinking of the input resistance of the COMP pin? If so, the resistance is very high, several mega ohms. But the capacitance in the comparator when the pin is sampled is quite high so the pin will draw some current. The COMP is not quite the same as the input of the ADC, but you can use the same principle as in this blog post: https://devzone.nordicsemi.com/nordic/nordic-blog/b/blog/posts/measuring-lithium-battery-voltage-with-nrf52

The input of the COMP have higher impedance than the ADC.