Complete, Isolated RS-485/RS-422
Data Interface
TERMINATING RESISTOR
(ONE RESISTOR ON EACH END)
B
DI
D
120Ω
DE
RO
A
A
B
A
B
R
100Ω
RE
R
R
RE
RE
D
D
RO DE
DI
RO DE
DI
TERMINATING RESISTOR
(ONE RESISTOR ON EACH END)
V
5V
IN
MAX1480A/B/C
V
V
CC1
AC1 (MAKE NO CONNECTION)
AC2 (MAKE NO CONNECTION)
1
2
28
27
26
25
24
23
22
21
20
19
18
17
16
15
CC2
C1
C2
ISO V
B
CC1
3
D1
D2
B
22µF
0.1µF
4
GND1
ISO RO DRV
A
120Ω
5
A
MAX487
MAX1487
MAX845
FS
6
R6
SD
ISO DI IN
ISO DE IN
ISO COM1
ISO DI DRV
SH
7
74HC86
OR EQUIVALENT
R4
R5
SHIELD
(OPTIONAL)
V
V
CC3
DI
8
R1
DI
DRIVER INPUT
NOTE: RESISTOR R7 PROTECTS
THE MAX1480A/B/C FROM
TRANSIENT CURRENTS
9
CC4
DE
10
11
12
13
14
R2
R3
BETWEEN SHIELD AND
TRANSMISSION LINES.
DE
DRIVER ENABLE
ISO V
CC2
R7
GND2
ISO DE DRV
ISO COM2
ISO RO LED
100Ω
RECEIVER OUTPUT
RO
RO
V
CC5
LOGIC GROUND ISOLATION BARRIER
ISOLATED COMMON
Figure 13. Typical Half-Duplex RS-485/RS-422 Network
______________________________________________________________________________________ 17
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
