JAJSHD6B August 2016 – May 2019 UCD90320
PRODUCTION DATA.
Using the V33A pin as ADC reference voltage by default provides a cost-effective solution. However, internal voltage reference has a higher Total Unadjusted Error. Also, voltage variations on the V33A pin affect ADC readings, such as when the device is powered down. In order to achieve better ADC accuracy, an external voltage reference can be connected to the VREFA+ and VREFA- pins. Ensure that the external reference voltage stays in regulation whenever V33D is above VBOR threshold. This limitation allows accurate ADC readings in full V33D operating range.
The external reference voltage level must be configured into the Fusion Digital Power Designer software to give correct ADC readings.