MAX220–MAX249
+5V-Powered, Multichannel RS-232
Drivers/Receivers
______________________________________________________________________________________ 33
400k
Ω
+10V TO -10V VOLTAGE INVERTER
+5V TO +10V VOLTAGE DOUBLER
V
CC
400k
Ω
GND
+5V
+5V
+5V
+5V
+5V
18
25
24
23
21
20
1
1
µ
F
1
µ
F
1
µ
F
1
µ
F
1
µ
F
14
3
16
5k
Ω
5k
Ω
5k
Ω
5k
Ω
5k
Ω
5k
Ω
5k
Ω
5k
Ω
ENTA
C2-
C2+
C1-
C1+
T
A1
OUT
T
A1
IN
T
A3
OUT
T
A3
IN
8R
A1
IN
10 R
A1
OUT
7R
A2
IN
11 R
A2
OUT
6R
A3
IN
12 R
A3
OUT
5R
A4
IN
13
19
R
A4
OUT
9
27
26
22
44
31
42
29
37
35
38
34
39
33
40
32
36ENRA
ENTB
V-
V+
T
B1
OUT
T
B1
IN
T
B3
OUT
T
B3
IN
R
B1
IN
R
B1
OUT
R
B2
IN
R
B2
OUT
R
B3
IN
R
B3
OUT
R
B4
IN
R
B4
OUT
ENRB
400k
Ω
+5V
2
15
T
A2
OUT
T
A2
IN
+5V
43
30
T
B2
OUT
T
B2
IN
400k
Ω
+5V
4
17
T
A4
OUT
T
A4
IN
+5V
41
28
T
B4
OUT
T
B4
IN
441234404142
43
5
21
24
26
25
27
28
22 2319
20
8
9
10
11
12
13
14
15
16
17
29
30
31
32
33
34
35
36
37
38
T
A4
IN
V
CC
R
A4
IN
MAX248
PLCC
TOP VIEW
T
A4
OUT
T
A3
OUT
T
A2
OUT
T
A1
OUT
T
B1
OUT
T
B2
OUT
T
B3
OUT
T
A4
OUT
R
B4
IN
GND
V+
C1+
C2+
C1-
V-
C2-
T
B4
IN
ENTB
R
B2
IN
R
B1
IN
R
B1
OUT
R
B2
OUT
R
B3
OUT
R
B4
OUT
T
B1
IN
T
B2
IN
T
B3
IN
T
A3
IN
T
A2
IN
T
A1
IN
R
A4
OUT
R
A3
OUT
R
A2
OUT
R
A1
OUT
ENRA
R
A1
IN
7
39
R
B3
IN
R
A2
IN
6
18
R
A3
IN
ENRB
ENTA
MAX248 FUNCTIONAL DESCRIPTION
8 RECEIVERS
4 A-SIDE RECEIVERS
4 B-SIDE RECEIVERS
8 TRANSMITTERS
4 A-SIDE TRANSMITTERS
4 B-SIDE TRANSMITTERS
4 CONTROL PINS
ENABLE RECEIVER A-SIDE (ENRA)
ENABLE RECEIVER B-SIDE (ENRB)
ENABLE RECEIVER A-SIDE (ENTA)
ENABLE RECEIVER B-SIDE (ENTB
)
Figure 24. MAX248 Pin Configuration and Typical Operating Circuit
