Q
When monitoring a voltage on the AVDD pin, what is the accuracy/stability of
the 1.17V internal reference used for analog-digital conversion?
A
For the AVDD monitor, an internal untrimmed 1.17V reference is used. AVDD is
divided by 6 and the attenuated voltage is used as the ADC input. Since the
internal reference is untrimmed, the conversion which reflects the ADC voltage
is not accurate. The AVDD monitor gives a coarse result rather than an accurate
result. The error could be as large as 1%.