By how much can positive input reference, Vrefp of the System Monitor, vary?
The specification in the datasheet for Vrefp is 2.45V to 2.55V, which is +/- 2%. However, this is qualified with the statement that any variation in the reference voltage from the nominal VREFP = 2.5V and VREFN = 0V will result in a deviation from the ideal transfer function. This also impacts the accuracy of the internal sensor measurements (i.e., temperature and power supply). However, for external ratiometric type applications, allowing the supply voltage and reference to vary by 2% is permitted.
In order to ensure accurate measurements of temperature and internal power supplies, the variance of Vrefp should not exceed +/- 0.2%.
Users should read the Reference Inputs section of the System Monitor User Guide (UG192).