The output from an ADC conversion is given by the following equations:
Single-Ended 12-bit conversion=VINP×GainVREF×4096∈[0,4095]
Single-Ended 8-bit conversion=VINP×GainVREF×256∈[0,255]
Differential 12-bit conversion=(VINP−VINN)×GainVREF×2048∈[-2048,2047]
Differential 8-bit conversion=(VINP−VINN)×GainVREF×128∈[-128,127]
V
INP and V
INN are the positive and
negative inputs to the ADC and V
REF is the selected voltage reference. The
gain is between 1x and 16x as configured in the PGA, and 1x if the PGA is not in
use.
The ADC has two output registers, the Sample (ADCn.SAMPLE) and Result
(ADCn.RESULT) registers. The 16-bit Sample register will always be updated with the
latest ADC conversion output (one sample). In Single conversion mode, both the Sample
(ADCn.SAMPLE) and Result (ADCn.RESULT) registers are identical.
With a Single-Ended 12-bit conversion, the voltage applied to the analog pin
is calculated by:
VINP=ADCn.SAMPLE×VREF4096×Gain