ADC input minimum current

[Pibbotley]

To use ADC attenuation I need to buffer the pins with voltage dividers. To minimise battery power and use highest resistances what is the minimum input current for an ESP32 analog input pin?

[Angus]

ADC input current will be neglible. However, to get the most accurate results from a high impedance source (like a high value voltage divider) you can add a small buffer capacitor (approx 100nF) between the ADC pin and ground.

[Pibbotley]

Excellent, thanks

[mura_lb]

ADC input current will be neglible. However, to get the most accurate results from a high impedance source (like a high value voltage divider) you can add a small buffer capacitor (approx 100nF) between the ADC pin and ground.

I have a similar problem, but not for ADC.
I need to detect the generation of very small current, through the transistor and optocoupler to form a simple detection circuit, output about 2uA logic level. Can ESP32 be confirmed with such a low current?

[Sprite]

I have a similar problem, but not for ADC.
I need to detect the generation of very small current, through the transistor and optocoupler to form a simple detection circuit, output about 2uA logic level. Can ESP32 be confirmed with such a low current?

Datasheet says input leakage is 50nA max, which is an order of magnitude smaller than the 2uA you have, so it should work.