m3819 Renesas Electronics Corporation., m3819 Datasheet - Page 46

• Manufacturer Part Number: m3819
• Description: Mitsubishi 8-bit Single-chip Microcomputer 740 Family / 38000 Series
• Manufacturer: Renesas Electronics Corporation.

Fig. 24 A-D converter block diagram
D-A CONVERTER
The 3819 group has internal D-A converter with 8-bit resolutions
1 channel.
D-A conversion is performed by setting the value in the D-A con-
version register. The result of D-A conversion is output from the
DA pin by setting the DA output enable bit to “1” . At this time, the
corresponding bit (PB
be set to “0” (input status).
The output analog voltage V is determined with the value n
(n: decimal number) in the D-A conversion register as follows:
V=V
At reset, the D-A conversion register is cleared to “00
output enable bits are cleared to “0”, and the PB
high impedance state. The D-A output does not build in a buffer, so
connect an external buffer when driving a low-impedance load.
Set V
Fig. 26 Equivalent connection circuit of D-A converter
32
D-A conversion
register
PB
REF
2
/DA
CC
V
REF
to 3.0 V or more when using the D-A converter.
n/256 (n=0 to 255)
: the reference voltage
"1"
P5
P5
P5
"0"
P5
P5
AV
V
P5
P5
REF
P5
3
5
7
2
6
/S
/S
/S
/S
/S
SS
4
Data bus
1
DA output enable bit
0
/S
/S
RDY2
OUT3
RDY3
CLK2
CLK3
/S
P7
P7
P7
P7
P7
P7
P7
P7
IN3
out2
IN2
2
/DA) of the port PB direction register should
0
1
2
3
4
5
6
7
/AN
/AN
/AN
/AN
/AN
/AN
AD-DA control register
/AN
/AN
/AN
/AN
/AN
/AN
/AN
/AN
/AN
/AN
(address 002C
10
11
12
13
14
15
MSB
0
1
2
3
4
5
6
7
8
9
"0"
"1"
2R
16
R
)
b7
2R
Comparator
2
4
/DA pin goes to
R
16
”, the DA
2R
A-D control circuit
R
A-D conversion register
Fig. 25 D-A converter block diagram
V
2R
Resistor ladder
REF
8
R
b0
(Address 002D
AV
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
SS
2R
R-2R resistor ladder
D-A conversion register (8)
R
16
MITSUBISHI MICROCOMPUTERS
)
2R
A-D conversion interrupt request
R
2R
DA output enable bit
3819 Group
R
2R
LSB
PB
2R
2
/DA