11.3.5 Sleep Mode Operation
If there is no ongoing write operation, the NVMCTRL will enter a sleep mode when the system enters a sleep mode.
If a write operation is ongoing when the system enters a sleep mode, the NVM block, the NVM Controller, and the system clock will remain ON until the write is finished, which is valid for all sleep modes, including the Power-Down sleep mode.
The EEPROM Ready and Flash Ready interrupts will only wake the device from Idle sleep mode.
The page buffer is cleared when waking up from sleep.