Datasheet

130
ATtiny25/45/85 [DATASHEET]
2586Q–AVR–08/2013
is used for reading the internal temperature sensor, as described in Section 17.12 on page 133. A good system
design with properly placed, external bypass capacitors does reduce the need for using ADC Noise Reduction
Mode
17.10 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, as follows:
• Offset: The deviation of the first transition (0x000 to 0x001) compared to the ideal transition (at 0.5 LSB). Ideal
value: 0 LSB.
Figure 17-9. Offset Error
• Gain Error: After adjusting for offset, the Gain Error is found as the deviation of the last transition (0x3FE to
0x3FF) compared to the ideal transition (at 1.5 LSB below maximum). Ideal value: 0 LSB
Output Code
V
REF
Input Voltage
Ideal ADC
Actual ADC
Offset
Error