7.1 Reference Voltages

Some analog peripherals require a reference voltage for proper operation.

Apart from external voltages (that is, VDDANA or VREFx), the device has a DETREF module that provides two different internal voltage references:
  • BANDGAP: A stable voltage reference, fixed at 1.1V.
  • INTREF: A variable voltage reference, configured by the Voltage References System Control register in the Supply Controller (SUPC.VREF).
The respective reference voltage source must be selected within each dedicated analog peripheral register:
  • ADC: Reference Control register (ADC.REFCTRL)
  • DAC: Reference Selection bits in the Control B register (DAC.CTRLB.REFSEL)
    Note: AC has a fixed reference voltage to BANDGAP value.