I am completing a schematic using the nRF51822 part. I will be supplying the part with a 3.3V supply. I will use one of the ADC inputs to sense battery voltage (up to 10v max and 4v min). A voltage divider circuit will obviously be needed on the AIN pin.
From the datasheet, it looks like VREF_EXT should be 1.2V and no greater than 1.3V. So does this mean if I am using an external voltage reference (my 3.3V supply) that I need a voltage divider on the AREF0 pin to decrease the voltage from 3.3V to 1.2V?
Is there any data on the accuracy of the internal reference voltage over temperature? Are there benefits to using the internal reference vs the external reference other than gaining an additional GPIO?
Would a capacitor in parallel to my AIN pin help with the accuracy of the ADC readings? If so, what would be an appropriate value?