Please refer to page 6 of ADuC7122 and page 7 of ADuC7023. In respective pages it is mentioned Buffer Enabled single-ended mode (ADuC7122) and External Reference input voltage range as 0 to AVdd.
Please suggest an alternate method to use an input and output range of 5V if above maximum rated voltage operation will degrade uC and its performance.
Please suggest the best external oscillator part which can be used with above microcontrollers.
As mentioned we do not guarantee any specification outside the recommended 2.7V to 3.6V operation nor do we have any quality data besides the parts survive the maximum rating.