ADC input minimum current

Pibbotley
Posts: 45
Joined: Fri Feb 16, 2018 7:06 pm

ADC input minimum current

Postby Pibbotley » Sun Feb 18, 2018 7:35 pm

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?

ESP_Angus
Posts: 2344
Joined: Sun May 08, 2016 4:11 am

Re: ADC input minimum current

Postby ESP_Angus » Mon Feb 19, 2018 6:22 am

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
Posts: 45
Joined: Fri Feb 16, 2018 7:06 pm

Re: ADC input minimum current

Postby Pibbotley » Mon Feb 19, 2018 9:28 am

Excellent, thanks

mura_lb
Posts: 12
Joined: Fri Jul 16, 2021 3:06 am

Re: ADC input minimum current

Postby mura_lb » Fri Oct 11, 2024 8:50 am

ESP_Angus wrote:
Mon Feb 19, 2018 6:22 am
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?

ESP_Sprite
Posts: 9715
Joined: Thu Nov 26, 2015 4:08 am

Re: ADC input minimum current

Postby ESP_Sprite » Sat Oct 12, 2024 2:53 am

mura_lb wrote:
Fri Oct 11, 2024 8:50 am
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.

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