The ADC modules share VREFHI and
VREFLO inputs. In external reference mode, these pins are used as a ratiometric
reference to determine the ADC conversion input range.
See Section 14.13.6 for information on how to supply the reference voltage.
Note:
- On devices with no external
VREFLO pin, VREFLO is internally
connected to the device analog ground, VSSA.
- See the device data sheet to
determine the allowable voltage range for VREFHI and VREFLO.
- The external reference mode
requires an external capacitor on the VREFHI pin. See the device data sheet
for the specific value required.