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IC BLOCK DIAGRAMS AND DESCRIPTIONS
uPD4721GS (RS-232C Driver/ Receiver)
Block diagram
V
1
DD
C
2
1
V
3
CC
C
4
1
C
5
S
C
6
S
D
7
IN1
D
8
IN2
R
9
OUT1
R
10
OUT2
TE
L 13942296513
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.
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Truth table
Driver
20
C
4
STBY
L
19
GND
H
18
C
4
H
17
V
SS
Receiver
STBY
16
STBY
L
15
V
CHA
H
300 ohm
14
D
OUT1
H
300 ohm
13
D
OUT2
3 V/5 V switching
V
CHA
12
R
IN1
5.5k ohm
L
11
R
IN2
H
5.5k ohm
x
ao
u163
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i
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2 9
8
D
D
Remarks
IN
OUT
X
Z
Standby mode (DC/DC converter is stopped)
L
H
Space level output
H
L
Mark level output
R
R
Remarks
IN
OUT
X
H
Standby mode (DC/DC converter is stopped)
L
H
Space level input
H
L
Space level input
Operating mode
5 V mode (double step-up)
3 V mode (3 times step-up)
Q Q
3
6 7
1 3
1 5
co
.
9 4
2 8
0 5
8
2 9
9 4
2 8
m
DTR-6.5
9 9
9 9
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