To internally monitor the ADC power supplies, use either ADC1 or ADC2. As shown in Figure 9-5, the power supply voltages are divided by a resistor network to reduce the voltages within the ADC input range. The reduced power-supply voltage is routed to the ADC input multiplexers. The analog (VANLMON) and digital (VDIGMON) power supply readings are scaled by Equation 10 and Equation 11, respectively:
Measure the supply monitor readings using either the internal or an external reference. For an external reference, the minimum reference voltage is 1.5 V.
Before measurement, enable the PGA, set gain = 1, and disable chop mode.
For analog supply monitor ADC1 measurement, set the INPMUX register (address 06h) to CCh.
For digital supply monitor ADC1 measurement, set the INPMUX register to DDh.
For analog supply monitor ADC2 measurement, set the ADC2MUX register (address 16h) to CCh.
For digital supply monitor ADC2 measurement, set the ADC2MUX register to DDh.