Power the UCD90320U device from a 3.3-V power supply.

If internal reference is used, V33A acts as ADC reference and is assumed to be exactly 3.3 V. Any input voltage deviation from 3.3 V introduces an error to ADC reference and to the ADC results. Therefore, the 3.3-V power supply must be tightly regulated and allow only a very small voltage fluctuation (including voltage ripple and voltage deviation caused by load transients).

If external reference is used, the 3.3-V power supply needs to meet only the minimum requirements specified in the Recommended Operating Conditions table and the Electrical Characteristics table.