M16C62_M Datasheet, PDF (452/615 Pages) Renesas Technology Corp – 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/60 SERIES

A-D Converter
Mitsubishi microcomputers
M16C / 62A Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
2.7.12 Method of A-D Conversion (8-bit mode)
(1) In 8-bit mode, 8 higher-order bits of the 10-bit successive comparison register becomes A-D
conversion result. Hence, if compared to a result obtained by using an 8-bit A-D converter,
the voltage compared is different by 3 VREF/2048 (see what are underscored in Table
2.7.12), and differences in stepping points of output codes occur as shown in Figure 2.7.24.
Table 2.7.12. The comparison voltage in 8-bit mode compared to 8-bit A-D converter
8-bit mode
8-bit A-D converter
Comparison
voltage
Vref
n=0
n = 1 to 255
0
VREF
2⁸
xn
– ^VREF
2¹⁰
x 0.5
0
VREF
2⁸
x
n – ^VREF
2⁸
x 0.5
Optimal conversion characteristics of 8-bit A-D converter (VREF = 5.12 V)
Output code
(Result of A-D conversion)
02
01
00
10
30
Analog input voltage (mV)
Optimal conversion characteristics in 8-bit mode (VREF = 5.12 V)
Output code
(Result of A-D conversion)
8-bit
mode
10-bit
mode
09
02
08
07
06
05
01
04
03
02
01
00
00
(Note)
10bit-mode
8bit-mode
17.5
37.5 Analog input voltage (mV)
Note: Differences in stepping points of output code for analog input voltage.
Figure 2.7.24. The level conversion characteristics of 8-bit mode and 8-bit A-D converter
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