+5V-Powered, Multichannel RS-232
Drivers/Receivers
+5V
TOP VIEW
1µF
1µF
20
21
C1+
C1-
V
22
CC
V+
V-
1µF
1µF
23
24
+5V TO +10V VOLTAGE DOUBLER
26
C2+
C2-
1µF
43
42 41 40
6
5
4
3
2
1
44
25
+10V TO -10V VOLTAGE INVERTER
18 ENTA
ENTB 27
+5V
+5V
+5V
+5V
+5V
+5V
1 T OUT
A1
T
OUT 44
B1
R
R
IN
IN
7
8
9
39
38
37
R IN
B3
R IN
B2
R IN
B1
A2
400k
400k
15 T IN
A1
T IN 30
B1
A1
ENRA
2 T OUT
A2
T
T
OUT 43
B2
R
R
R
R
R
OUT 10
OUT 11
OUT 12
OUT 13
36 ENRB
A1
A2
A3
A4
35
34
33
32
31
30
29
R
R
R
R
R
OUT
OUT
OUT
OUT
OUT
B1
B2
B3
B4
B5
MAX249
16 T IN
T IN 29
B2
A2
3 T OUT
A3
OUT 42
B3
14
15
OUT
A5
T
400k
IN
A1
A2
A3
17 T IN
T
IN 28
IN 37
A3
B3
T
T
IN 16
IN 17
T
T
IN
B1
B2
8 R IN
R
B1
A1
IN
5k
5k
5k
5k
5k
5k
18 19 20 21 22 23 24 25 26 27 28
10 R OUT
R
OUT 35
A1
B1
7 R IN
R
IN 38
B2
A2
PLCC
5k
11 R OUT
R
OUT 34
B2
A2
MAX249 FUNCTIONAL DESCRIPTION
10 RECEIVERS
5 A-SIDE RECEIVERS
5 B-SIDE RECEIVERS
6 TRANSMITTERS
3 A-SIDE TRANSMITTERS
3 B-SIDE TRANSMITTERS
4 CONTROL PINS
6 R IN
R
IN 39
B3
A3
5k
12 R OUT
R
OUT 33
B3
A3
5 R IN
R
IN 40
B4
A4
5k
ENABLE RECEIVER A-SIDE (ENRA)
ENABLE RECEIVER B-SIDE (ENRB)
ENABLE RECEIVER A-SIDE (ENTA)
ENABLE RECEIVER B-SIDE (ENTB)
13 R OUT
R
OUT 32
B4
A4
4 R IN
R
IN 41
B5
A5
5k
14 R OUT
A5
R
OUT 31
B5
9 ENRA
ENRB 36
GND
19
Figure 25. MAX249 Pin Configuration and Typical Operating Circuit
34 ______________________________________________________________________________________