66.9.2 External Reference Voltage

VADVREF is an external reference voltage applied on the pin ADVREF. The quality of the reference voltage VADVREF is critical to the performance of the ADC. A DC variation of the reference voltage VADVREF is converted to a gain error by the ADC. The noise generated by VADVREF is converted by the ADC to count noise.

Table 66-30. ADVREF Electrical Characteristics
Symbol Parameter Conditions Min Typ Max Unit
VADVREF Voltage Range Full operational 2 VDDANA V
RMS Noise Bandwidth 10 kHz to 1 MHz 100 µV
RADVREF Input DC Impedance ADC reference resistance bridge(1) 6 8 10
IADVREF Current VADVREF = 3.3V 460 µA
Note:
  1. When the ADC is off, the ADVREF impedance has a minimum of 1 MΩ.