A-D Converter
189
Mitsubishi microcomputers
M16C / 62P Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
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 AV
CC
(V
CC1
)
Operating clock
φ
AD
(Note 2)
f
AD
/divide-by-2 of f
AD
/divide-by-3 of f
AD
/divide-by-4 of f
AD
/divide-by-6 of
f
AD
/divide-by-12 of f
AD
Resolution
8-bit or 10-bit (selectable)
Integral nonlinearity error
When AV
CC
= V
REF
= 5V
With 8-bit resolution:
±
2LSB
With 10-bit resolution
- AN
0
to AN
7
input :
±
3LSB
- AN
00
to AN0
7
input and AN
20
to AN
27
input :
±
7LSB
- ANEX0 and ANEX1 input (including mode in which external operation
amp is connected) :
±
7LSB
When AV
CC
= V
REF
= 3.3V
With 8-bit resolution:
±
2LSB
With 10-bit resolution
- AN
0
to AN
7
input :
±
5LSB
- AN
00
to AN0
7
input and AN
20
to AN
27
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 (AN
0
to AN
7
) + 2 pins (ANEX0 and ANEX1) + 8 pins (AN
00
to AN
07
)
+ 8 pins (AN
20
to AN
27
)
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 AD
TRG
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
φ
AD
cycles
,
10-bit resolution: 59
φ
AD
cycles
With sample and hold function
8-bit resolution: 28
φ
AD
cycles
,
10-bit resolution: 33
φ
AD
cycles
Note 1: Does not depend on use of sample and hold function.
Note 2: The f
AD
frequency must be 10 MHz or less.
Without sample-and-hold function, limit the f
AD
frequency to 250kH
Z
or less.
With the sample and hold function, limit the f
AD
frequency to 1MH
Z
or less.
Note 3: If V
CC2
< V
CC1
, do not use AN
00
to AN
07
and AN
20
to AN
27
as analog input pins.
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 P10
0
to P10
7
, P9
5
,
P9
6
, P0
0
to P0
7
, and P2
0
to P2
7
. Similarly, AD
TRG
input shares the pin with P9
7
. 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 V
REF
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