Reference Voltages

Some analog peripherals require a reference voltage for proper operation.

Apart from external voltages (that is, V_DDANA or V_REFx), 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.