32.2.4 ADC Operation During Sleep
The ADC module can operate during Sleep. This requires the ADC clock
source to be set to internal RC oscillator (the CS bit in the ADCON0
register is set to ‘1’). When the FRC is selected as ADC clock
source, the ADC waits one additional instruction before starting the conversion. This
allows the SLEEP instruction to be executed, which can reduce system noise
during the conversion. If the ADC interrupt is enabled, the device will wake up from Sleep
when the conversion completes. If the ADC interrupt is disabled, the ADC module is turned
off after the conversion completes, although the ON bit remains
set.