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A-D Converter
189
Mitsubishi microcomputers
M16C / 62P Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
Under
development
Preliminary Specifications Rev.1.0
Specifications in this manual are tentative and subject to change.
Item
Performance
Method of A-D conversion Successive approximation (capacitive coupling amplifier)
Analog input voltage (Note 1) 0V to AVCC (VCC1)
Operating clock
φAD (Note 2) fAD/divide-by-2 of fAD/divide-by-3 of fAD/divide-by-4 of fAD/divide-by-6 of
fAD/divide-by-12 of fAD
Resolution
8-bit or 10-bit (selectable)
Integral nonlinearity error
When AVCC = VREF = 5V
With 8-bit resolution:
±2LSB
With 10-bit resolution
- AN0 to AN7 input :
±3LSB
- AN00 to AN07 input and AN20 to AN27 input :
±7LSB
- ANEX0 and ANEX1 input (including mode in which external operation
amp is connected) :
±7LSB
When AVCC = VREF = 3.3V
With 8-bit resolution:
±2LSB
With 10-bit resolution
- AN0 to AN7 input :
±5LSB
- AN00 to AN07 input and AN20 to AN27 input :
±7LSB
- ANEX0 and ANEX1 input (including mode in which external operation
amp is connected) :
±7LSB
Operating modes
One-shot mode, repeat mode, single sweep mode, repeat sweep mode 0,
and repeat sweep mode 1
Analog input pins
8 pins (AN0 to AN7) + 2 pins (ANEX0 and ANEX1) + 8 pins (AN00 to AN07)
+ 8 pins (AN20 to AN27)
A-D conversion start condition Software trigger
The ADCON0 register's ADST bit is set to “1” (A-D conversion starts)
External trigger (retriggerable)
___________
Input on the ADTRG pin changes state from high to low after the ADST bit is
set to “1” (A-D conversion starts)
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
A-D Converter
The microcomputer contains one A-D converter circuit based on 10-bit successive approximation method
configured with a capacitive-coupling amplifier. The analog inputs share the pins with P100 to P107, P95,
___________
P96, P00 to P07, and P20 to P27. Similarly, ADTRG input shares the pin with P97. Therefore, when using
these inputs, make sure the corresponding port direction bits are set to “0” (= input mode).
When not using the A-D converter, set the VCUT bit to “0” (= Vref unconnected), so that no current will flow
from the VREF pin into the resistor ladder, helping to reduce the power consumption of the chip.
The A-D conversion result is stored in the ADi register bits for ANi, AN0i, and AN2i pins (i = 0 to 7).
Table 1.22.1 shows the performance of the A-D converter. Figure 1.22.1 shows the block diagram of the
A-D converter, and Figures 1.22.2 and 1.22.3 show the A-D converter-related registers.
Table 1.22.1. Performance of A-D Converter
Note 1: Does not depend on use of sample and hold function.
Note 2: The fAD frequency must be 10 MHz or less.
Without sample-and-hold function, limit the fAD frequency to 250kHZ or less.
With the sample and hold function, limit the fAD frequency to 1MHZ or less.
Note 3: If VCC2 < VCC1, do not use AN00 to AN07 and AN20 to AN27 as analog input pins.