19.2 Overview

The Voltage Reference (VREF) peripheral provides control registers for the voltage reference sources used by several peripherals. The user can select the reference voltages for the ADCn by writing to the ADCn Reference Select (ADCnREFSEL) bit field in the Control x (VREF.CTRLx) registers, and for both ACn and DACn by writing to the DACn Reference Select (DACnREFSEL) bit field in the Control x (VREF.CTRLx) registers.

A voltage reference source is enabled automatically when requested by a peripheral. The user can enable the reference voltage sources (and thus, override the automatic disabling of unused sources) by writing to the respective Force Enable (ADCnREFEN, DACnREFEN) bit in the Control B (VREF.CTRLB) register. This may be done to decrease the start-up time, at the cost of increased power consumption.