Datasheet

228
8284D–AVR–6/11
ATmega169A/PA/329A/PA/3290A/PA/649A/P/6490A/P
23.7.3 ADC Accuracy Definitions
An n-bit single-ended ADC converts a voltage linearly between GND and V
REF
in 2
n
steps
(LSBs). The lowest code is read as 0, and the highest code is read as 2
n
-1.
Several parameters describe the deviation from the ideal behavior:
• Offset: The deviation of the first transition (0x000 to 0x001) compared to the ideal transition (at
0.5 LSB). Ideal value: 0 LSB.
Figure 23-10. Offset Error
Output Code
V
REF
Input Voltage
Ideal ADC
Actual ADC
Offset
Error