For basic operation, follow these steps:
  1. 1.Configure the desired input pins in the port peripheral.
  2. 2.Select the positive and negative input sources by writing the Positive and Negative Input MUX Selection (MUXPOS and MUXNEG) bit fields in the MUX Control A (ACn.MUXCTRLA) register.
  3. 3.Optional: Enable the output to pin by writing a ‘1’ to the Output Pad Enable (OUTEN) bit in the Control A (ACn.CTRLA) register.
  4. 4.Enable the AC by writing a ‘1’ to the ENABLE bit in the ACn.CTRLA register.

During the start-up time after enabling the AC, the output of the AC may be invalid.

The start-up time of the AC by itself is at most 2.5 µs. If an internal reference is used, the reference start-up time is normally longer than the AC start-up time. The VREF start-up time is 60 µs at most.