https://devzone.nordicsemi.com/f/nordic-q-a/12162/adc-wrong-valuesHi I have nrf51822 CEAA which is powered with 1.9 volt on vdd (low power chip). I&#39;m using ADC to measure battery level but the conversion gave me 5.4 volt wich is wrong for the battery here my adc configuration NRF_ADC-&gt;INTENSET = (ADC_INTENSET_END_Disableden-USTelligent Community 13Mon, 29 Feb 2016 15:44:05 GMThttps://devzone.nordicsemi.com/thread/46026?ContentTypeID=1Mon, 29 Feb 2016 15:44:05 GMT137ad170-7792-4731-bb38-c0d22fbe4515:2f8102f6-7d98-4627-bc95-5788e73d93dcOle Bauck<p>The maximum rating on a gpio pin is VDD+0.3V, see product specification absolute maximum ratings. This means that the maximum voltage in your case is 2.2V (1.9V+0.3V), so you will need a voltage divider from the battery to the gpio pin. I would configure the voltage divider such that the maximum voltage on the pin is 1.2V (VBG) and then used AnalogInputNoPrescaling and refsel VBG to utilize the full range of the ADC.</p> <p>I don&#39;t know why you are measuring 5.4V, but since you are outside the operating conditions for the chip it doesn&#39;t matter.</p><div style="clear:both;"></div>