How to be able to do adc reading from external 9V Litum battery ?

RE: How to be able to do adc reading from external 9V Litum battery ?

Jørgen Holmefjord — Wed, 02 Sep 2020 08:23:45 GMT

A Li-Po battery rated at 3.7V is typically the nominal voltage, while the maximum charge current is typically around 4.2V. You can not input this high voltage to the GPIOs of the nRF52, as this is outside of the absolute maximum and recommended operating conditions.

The SAADC can read values between GND and VDD if configured for full-range input. Above VDD, the samples will be incorrect. If there is a change that the input will be over VDD, you should use a voltage divider circuit.

RE: How to be able to do adc reading from external 9V Litum battery ?

Jaehong Park — Tue, 01 Sep 2020 16:01:40 GMT

By the way, about 3.7V Li-Po battery on spec., can we read adc value from the battery using p0.04(A1) without external voltage divider circuits?
In fact, 3.7V battery outputs 4V after checking the volatage of the battery using multimeter.

In nRF52832 PS doc, analogue input ranges from ?? value to VDD(3.7V ??).
Then can we read the adc value from the battery directly without the external voltage divider?

RE: How to be able to do adc reading from external 9V Litum battery ?

Jørgen Holmefjord — Mon, 31 Aug 2020 07:39:30 GMT

Hi,

Please have a look at this blog post: Measuring Lithium battery voltage with nRF52.

Best regards,
Jørgen