31.3.3 Sleep Mode Operation
If the Run in Standby (RUNSTDBY) bit in the Control A (DACn.CTRLA) register is written to
                ‘1’ and CLK_PER is available, the DAC will continue to operate in
            Standby sleep mode. If the RUNSTDBY bit is ‘0’, the DAC will stop the
            conversion in Standby sleep mode.
If the conversion is stopped in Standby sleep mode, the DAC and the output buffer are
            disabled to reduce power consumption. When the device is exiting Standby sleep mode, the
            DAC and the output buffer (if configured by OUTEN = ‘1’ in DACn.CTRLA)
            are enabled again. Therefore, a certain start-up time is required before a new
            conversion is initiated.
In Power-Down sleep mode, the DAC and output buffer are disabled to reduce power consumption.
