38.4.6 ADC Voltage Reference Selection

The ADC positive voltage reference can be externally driven on the VREFP pin or internally driven by the embedded regulator. Refer to the section “Electrical Characteristics” for the driving capability of pin VREFP when it is internally driven.

When the voltage is internally driven, the embedded regulator must be enabled and an external decoupling capacitor must be connected to VREFP.

When the voltage is externally driven, the internal regulator must be turned off.

The internal regulator is enabled by writing ADC_ACR.INTVREFEN to 1.

Refer to the section “Electrical Characteristics” for further details.