Onkyo TX-SR702 Service Manual page 59

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
Truth table
Driver
20
C
4 STBY D
IN
L X
19
GND
H L
18
C
4
H H
17
V
SS
Receiver
R
IN
STBY
16
STBY
X
L
15
V
CHA
L
H
300 ohm
14
D
OUT1
H
H
300 ohm
13 D
OUT2
3 V/5 V switching
V Operating mode
CHA
12 R
IN1
5.5k ohm
L 5 V mode (double step-up)
11 R
IN2
H 3 V mode (3 times step-up)
5.5k ohm
D Remarks
OUT
Z Standby mode (DC/DC converter is stopped)
H Space level output
L Mark level output
R Remarks
OUT
H Standby mode (DC/DC converter is stopped)
H Space level input
L Space level input
TX-SR702/E