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Rev. 1.0, 07/01, page 262 of 372
16.5 A/D Conversion Accuracy Definitions
This LSI's A/D conversion accuracy definitions are given below.
•
Resolution
The number of A/D converter digital output codes
•
Quantization error
The deviation inherent in the A/D converter, given by 1/2 LSB (see figure 16-4).
•
Offset error
The deviation of the analog input voltage value from the ideal A/D conversion characteristic
when the digital output changes from the minimum voltage value 0000000000 to 0000000001
(see figure 16-5).
•
Full-scale error
The deviation of the analog input voltage value from the ideal A/D conversion characteristic
when the digital output changes from 1111111110 to 1111111111 (see figure 16-5).
•
Nonlinearity error
The deviation from the ideal A/D conversion characteristic as the voltage changes from zero to
full scale. This does not include the offset error, full-scale error, or quantization error.
•
Absolute accuracy
The deviation between the digital value and the analog input value. Includes offset error, full-
scale error, quantization error, and nonlinearity error.
111
110
101
100
011
010
001
000
1
8
2
8
6
8
7
8
FS
Quantization error
Digital output
Ideal A/D conversion
characteristic
Analog
input voltage
3
8
4
8
5
8
Figure 16-4 A/D Conversion Accuracy Definitions (1)