36.6.1 Principle of Operation
By default, the ADC provides results with 12-bit resolution. 8-bit or 10-bit results can be selected in order to reduce the conversion time, see 36.6.2.8 Conversion Timing and Sampling Rate.
The ADC has an oversampling with decimation option that can extend its resolution to 16 bits. The input values can be either internal or external (connected I/O pins). The user can also configure whether the conversion should be single-ended or differential.