SH7065 Datasheet, PDF (639/941 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH RISC engine Family/SH7000 Series

Section 15 A/D Converter
15.5 Interrupt Sources and DMA Transfer Requests
The A/D converter generates an A/D conversion end interrupt (ADI) on completion of A/D
conversion. The ADI interrupt can be enabled or disabled with the ADIE bit in ADCSR. DMA
transfer can be initiated by an ADI interrupt.
When the DMAC is activated by an ADI interrupt, the ADF bit in the A/D control/status register
(ADCSR) is automatically cleared to 0 when an A/D register is accessed.
15.6 A/D Conversion Accuracy Definitions
The A/D converter converts analog values input from analog input channels to 10-bit digital
values by comparing them with an analog reference voltage. In this operation, the absolute
accuracy of the A/D conversion (i.e. the deviation between the input analog value and the output
digital value) includes the following kinds of error.
1. Offset error
2. Full-scale error
3. Quantization error
4. Nonlinearity error
The above four kinds of error are described below with reference to figure 15.7. For the sake of
clarity, this figure shows 3-bit A/D conversion rather than 10-bit A/D conversion. Offset error (see
figure 15.7 (1)) is the deviation between the actual A/D conversion characteristic and the ideal
A/D conversion characteristic when the digital output value changes from the minimum value
(zero voltage) of 0000000000 (000 in the figure) to 0000000001 (001 in the figure ). Full-scale
error (see figure 15.7 (2)) is the deviation between the actual A/D conversion characteristic and the
ideal A/D conversion characteristic when the digital output value changes from 1111111110 (110
in the figure) to the maximum value (full-scale voltage) of 1111111111 (111 in the figure).
Quantization error is the deviation inherent in the A/D converter, given by 1/2 LSB (see figure
15.7 (3)). Nonlinearity error is the deviation between the actual A/D conversion characteristic and
the ideal A/D conversion characteristic from zero voltage to full-scale voltage (see figure 15.7
(4)). This does not include offset error, full-scale error, and quantization error.
Rev. 5.00 Sep 11, 2006 page 617 of 916
REJ09B0332-0500