Onkyo DX-C34 Service Manual page 33

IC BLOCK DIAGRAM / TERMINAL DESCRIPTION
Q851: MPD4721GS RS-232C LINE DRIVER/ RECEIVER
BLOCK DIAGRAM
+10V
V
1
DD
+
C
3
2 C +
1
+3.3V
3 V
CC
or
+5V
+
C
1
4 C -
1
5 C +
5
+
C
5
6 C -
5
7
D
IN1
8
D
IN2
9
R
OUT1
10
R
OUT2
Truth table
Driver
STBY D
L x
H L
H H
Receiver
STBY R
L x
H L
H H
3V 5V switching
V
CHA
5 V mode (double step-up)
L
3 V mode (3 times step-up)
H
H : high-level, L : low-level, Z : high-impedance, x : H or L
C
4+
GND
C
4-
V
SS
NOTE1
300 ohm
300 ohm
5.5k ohm
5.5k ohm
Top View
D Remarks
IN OUT
Standby mode
Z
Space level output
H
Mark level output
L
R Remarks
IN OUT
H Standby mode
H Mark level input
L Space level input
Operating mode
20
+
C
4
19
+
C
18 2
-10V
17
STBY
16
V
15 CHA
D
14
OUT1
D
13
OUT2
R
12
IN1
R
11 IN2
20 Pin Plastic Shrink SOP
20 11
1 10
DX-C34