M30218_01 Datasheet, PDF (130/469 Pages) Renesas Technology Corp – 16-BIT SINGLE-CHIP MICROCOMPUTER

A-D converter
Mitsubishi microcomputers
M30218 Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
A-D Converter
The A-D converter consists of one 10-bit successive approximation A-D converter circuit with a capacitive
coupling amplifier. Pins P100 to P107 also function as the analog signal input pins. The direction registers of
these pins for A-D conversion must therefore be set to input. The Vref connect bit (bit 5 at address 03D7 16)
can be used to isolate the resistance ladder of the A-D converter from the reference voltage input pin (VREF)
when the A-D converter is not used. Doing so stops any current flowing into the resistance ladder from
VREF, reducing the power dissipation. When using the A-D converter, start A-D conversion only after setting
bit 5 of 03D716 to connect VREF.
The result of A-D conversion is stored in the A-D registers of the selected pins. When set to 10-bit precision,
the low 8 bits are stored in the even addresses and the high 2 bits in the odd addresses. When set to 8-bit
precision, the low 8 bits are stored in the even addresses.
Table 30 shows the performance of the A-D converter. Figure 101 shows the block diagram of the A-D
converter, and Figures 102 and 103 show the A-D converter-related registers.
Table 30. Performance of A-D converter
Item
Performance
Method of A-D conversion Successive approximation (capacitive coupling amplifier)
Analog input voltage (Note 1) 0V to AVCC (VCC)
Operating clock φAD (Note 2) VCC = 5V fAD/divide-by-2 of fAD/divide-by-4 of fAD, fAD=f(XIN)
VCC = 3V divide-by-2 of fAD/divide-by-4 of fAD, fAD=f(XIN)
Resolution
8-bit or 10-bit (selectable)
Absolute precision
VCC = 5V • Without sample and hold function
±3LSB
• With sample and hold function (8-bit resolution)
±2LSB
• Without sample and hold function (10-bit resolution)
±3LSB
VCC = 3V • Without sample and hold function (8-bit resolution)(Note 3)
±2LSB
Operating modes
One-shot mode, repeat mode, single sweep mode, repeat sweep mode 0,
and repeat sweep mode 1
Analog input pins
8pins (AN0 to AN7)
A-D conversion start condition •Software trigger
A-D conversion starts when the A-D conversion start flag changes to “1”
Conversion speed per pin •Without sample and hold function
8-bit resolution: 49 φAD cycles, 10-bit resolution: 59 φAD cycles
• With sample and hold function
8-bit resolution: 28 φAD cycles, 10-bit resolution: 33 φAD cycles
Note 1: Does not depend on use of sample and hold function.
Note 2: Without sample and hold function, set the φAD frequency to 250kHz min.
With the sample and hold function, set the φAD frequency to 1MHz min.
Note 3: Only mask ROM version.
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