34.7 Operation in Sleep
The NCO module operates independently from the system clock and will continue to run during Sleep, provided that the clock source selected remains active.
The HFINTOSC remains active during Sleep when the NCO module is enabled and the HFINTOSC is selected as the clock source, regardless of the system clock source selected.
In other words, if the HFINTOSC is simultaneously selected as the system clock and the NCO clock source, when the NCO is enabled, the CPU will go Idle during Sleep, but the NCO will continue to operate and the HFINTOSC will remain active.
With a clock running, it will have a direct effect on the Sleep mode current.