SBAS991 February 2021 ADC3663
For highest accuracy and lowest temperature drift, the VREF input can be directly connected to an external 1.6 V reference. A 10 uF and a 0.1 uF ceramic bypass capacitor (CVREF) connected between the VREF and REFGND pins and placed as close to the pins as possible is recommended. The load current from the external reference is about 1 mA.
Note: The internal reference is also used for other functions inside the device, therefore the reference amplifier should only be powered down in power down state but not during normal operation.