Datasheet

MAX3480EA/MAX3480EB
±15kV ESD-Protected, Isolated, 3.3V
RS-485/RS-422 Data Interfaces
______________________________________________________________________________________ 15
Figure 11. Typical RS-485/RS-422 Network
DI
DE
RO
BA
R
D
RE
RO
DE
DI
R
120
Ω
D
A
B
RERE
DI
DE
RO
BA
R
D
AC1 (MAKE NO CONNECTION)
AC2 (MAKE NO CONNECTION)
SHIELD
(OPTIONAL)
ISO V
CC1
B
D2
D1
V
CC2
V
CC1
ISO RO DRV
A
B
A
SH
ISO DI IN
ISO DE IN
V
CC3
SD
FS
GND1
ISO COM1
ISO DI DRV
ISO V
CC2
ISO DE DRV
DE
GND2
V
CC4
DI
ISO COM2
ISO RO LED
V
CC5
RO
R4*
R7*
R5*
R8
100
Ω
120Ω
R6*
MAX3480EA/EB
LOGIC GROUND
*SEE TABLE 1.
ISOLATION BARRIER
TERMINATING RESISTOR
(ONE RESISTOR ON EACH END)
MAX845
MAX1487E
MAX487E
1
2
28
27
3
4
5
6
7
8
9
10
11
12
13
14
26
25
24
23
22
21
20
19
18
17
16
15
TERMINATING RESISTOR
(ONE RESISTOR ON EACH END)
D1, D2
1N914
R1*
R2*
R3*
BOOSTED V+
DRIVER INPUT
DRIVER ENABLE
V
IN
+3.0V TO +3.6V
C1
22µF
6V
C2
0.1µF
C3
0.01µF
C4
270pF
4kV
16
14
12
5
7
13
15
8 2
DI
DE
RO
17
20
18
3
9
10
11
RECEIVER OUTPUT
6
4
74HC240
NOTE: RESISTOR R8
PROTECTS THE MAX3480E
FROM TRANSIENT
CURRENTS BETWEEN
SHIELD AND A AND B.
ISOLATION
COMMON