SH7261 Datasheet, PDF (1064/1348 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7260 Series

Section 22 A/D Converter (ADC)
These four error quantities are explained below with reference to figure 22.7. In the figure, the 10
bits of the A/D converter have been simplified to 3 bits. Offset error is the deviation between
actual and ideal A/D conversion characteristics when the digital output value changes from the
minimum (zero voltage) B'0000000000 (000 in the figure) to B'000000001 (001 in the figure)
(figure 22.7, item (1)). Full-scale error is the deviation between actual and ideal A/D conversion
characteristics when the digital output value changes from B'1111111110 (110 in the figure) to the
maximum B'1111111111 (111 in the figure) (figure 22.7, item (2)). Quantization error is the
intrinsic error of the A/D converter and is expressed as 1/2 LSB (figure 22.7, item (3)).
Nonlinearity error is the deviation between actual and ideal A/D conversion characteristics
between zero voltage and full-scale voltage (figure 22.7, item (4)). Note that it does not include
offset, full-scale, or quantization error.
Digital output
Digital output
(2) Full-scale error
Ideal A/D
111
conversion
characteristic
110
101
100
011
010
(3) Quantization
error
001
000
01 ₂
10241024
[Legend]
FS: Full-scale voltage
10221023 ^FS
10241024 Analog input
voltage
Ideal A/D
conversion
characteristic
(4) Nonlinearity
error
Actual A/D
convertion
characteristic
(1) Offset error
FS
Analog input
voltage
Figure 22.7 Definitions of A/D Conversion Accuracy
Rev. 2.00 Sep. 07, 2007 Page 1032 of 1312
REJ09B0320-0200