The AFEx8101 family of devices includes a 1.25-V precision band-gap reference. The internal reference is externally available at the VREFIO pin and sources up to 2.5 mA. For noise filtering, use a 100-nF capacitor between the reference output and GND.

The internal reference circuit is enabled or disabled by using the REF_EN pin. A logic high on this pin enables the internal reference, and the VREFIO pin outputs 1.25 V. A logic low on this pin disables the internal reference, and the device expects to have 1.25 V from external VREF at the VREFIO pin.

An invalid reference voltage asserts an alarm condition. The DAC response depends on the VREF_FLT setting in the ALARM_ACT register (10h).