SH7727 Datasheet, PDF (947/1109 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH RISC engine Family/SH7700 Series

Section 28 A/D Converter
28.5 Interrupts
The A/D converter generates an interrupt (ADI) at the end of A/D conversion. The ADI interrupt
request can be enabled or disabled by the ADIE bit in ADCSR.
28.6 Definitions of A/D Conversion Accuracy
The A/D converter compares an analog value input from an analog input channel to its analog
reference value and converts it into 10-bit digital data. The absolute accuracy of this A/D
conversion is the deviation between the input analog value and the output digital value. It includes
the following errors:
• Offset error
• Full-scale error
• Quantization error
• Nonlinearity error
These four error quantities are explained below using figure 28.8. 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) 0000000000 (000 in the figure) to
000000001 (001 in the figure)(figure 28.8, item (1)). Full-scale error is the deviation between
actual and ideal A/D conversion characteristics when the digital output value changes from the
1111111110 (110 in the figure) to the maximum 1111111111 (111 in the figure)(figure 28.8, item
(2)). Quantization error is the intrinsic error of the A/D converter and is expressed as 1/2 LSB
(figure 28.8, item (3)). Nonlinearity error is the deviation between actual and ideal A/D conversion
characteristics between zero voltage and full-scale voltage (figure 28.8, item (4)). Note that it does
not include offset, full-scale or quantization error.
Rev. 5.00 Dec 12, 2005 page 875 of 1034
REJ09B0254-0500