The ADPCH
register determines which input channels
are connected to the Sample-and-Hold circuit for conversion. When switching channels, it
is recommended to have some acquisition time (ADACQ
register) before starting the next conversion. Refer to the ADC Operation
section for more information.
Important: To reduce the chance of
measurement error, it is recommended to discharge the Sample-and-Hold capacitor when
switching between ADC channels by starting a conversion on a channel connected to VSS and terminating the conversion after the
acquisition time has elapsed. If the ADC does not have a dedicated VSS input channel, the VSS selection through the DAC output channel can
be used. If the DAC is in use (or the device does not have a DAC), a free input channel
can be connected to VSS, and can be used in
place of the DAC.