+ 5V供电，多通道RS - 232
驱动器/接收器
MAX220–MAX249
顶视图
1F
21
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
A3
IN
R
A4
IN
R
B4
IN
1F
1F
20
V
CC
+ 5V至+ 10V电压DOUBLER
+ 10V至-10V的电压逆变器
ENTB 27
+5V
1 T
A1
OUT
R
A2
IN
R
A1
IN
ENRA
R
A1
OUT
R
A2
OUT
R
A3
OUT
R
A4
OUT
T
A1
IN
T
A2
IN
T
A3
IN
T
A4
IN
7
8
9
10
11
12
13
14
15
16
17
18
19 20 21 22 23 24 25 26 27 28
39
R
B3
IN
38
R
B2
IN
37
R
B1
IN
36
ENRB
+5V
1F
6
5
4
3
2
1
44 43 42 41 40
C1+
23 C1-
24
C2+
25 C2-
18 ENTA
V+
V-
22
26
1F
+5V
T
B1
OUT 44
400k
14 T
A1
IN
+5V
2 T
A2
OUT
400k
15 T
A2
IN
+5V
3 T
A3
OUT
400k
16 T
A3
IN
+5V
4 T
A4
OUT
400k
17 T
A4
IN
8 R
A1
IN
5k
T
B4
28
R
B1
37
5k
R
B1
出35
R
B2
38
5k
R
B2
出34
R
B3
39
5k
R
B3
OUT 33
R
B4
40
5k
R
B4
OUT 32
ENRB 36
GND
19
+5V
T
B4
OUT 41
T
B3
29
+5V
T
B3
OUT 42
T
B2
在30
+5V
T
B2
OUT 43
T
B1
31
MAX248
35
R
B1
OUT
34
R
B2
OUT
33
R
B3
OUT
32
R
B4
OUT
31
T
B1
IN
30
T
B2
IN
29
T
B3
IN
GND
C1-
C1+
C2+
C2-
V+
V-
PLCC
MAX248功能说明
8接收机
4 A- SIDE接收机
4 B- SIDE接收机
8变送器
4人制变送器
4 B- SIDE变送器
4控制引脚
ENABLE接收器端（ ENRA ）
启用收件人B- SIDE （ ENRB ）
ENABLE接收器端（ ENTA ）
启用收件人B- SIDE （ ENTB
)
T
B4
IN
ENTA
ENTB
V
CC
10 R
A1
OUT
7 R
A2
IN
5k
11 R
A2
OUT
6 R
A3
IN
5k
12 R
A3
OUT
5 R
A4
IN
5k
13 R
A4
OUT
9 ENRA
图24. MAX248引脚配置和典型工作电路
______________________________________________________________________________________
33
