MAX3480EA Datasheet, PDF (15/16 Pages) Maxim Integrated Products – +-15kV ESD-Protected, Isolated, 3.3V RS-485/RS-422 Data Interfaces

±15kV ESD-Protected, Isolated, 3.3V
RS-485/RS-422 Data Interfaces
AB
TERMINATING RESISTOR
(ONE RESISTOR ON EACH END)
AB
B
120Ω
A
RE
R
D
RO DE
DI
RE
R
D
RO DE DI
DI
D
DE
R
RO
RE
VIN
+3.0V TO +3.6V _C1
22µF
6V
C2
0.1µF
D1, D2
1N914
BOOSTED V+
C3
0.01µF
74HC240 4
16
6
14
18
DI ²
8
12 DRIVER INPUT
R1*
DE ^{17 3}
15
5
DRIVER ENABLE
R2*
13
7
20
RO
9
11
10
RECEIVER OUTPUT
R3*
V_{CC1 1}
V_{CC2 2}
D1 ₃
D2 ₄
GND1 ₅
FS ₆
SD ₇
V_CC3
8
DI ₉
V_{CC4 10}
DE ₁₁
GND2 ₁₂
RO ₁₃
V_{CC5 14}
*SEE TABLE 1.
LOGIC GROUND
MAX3480EA/EB
MAX845
MAX485E
MAX487E
ISOLATION BARRIER
C4
270pF
4kV
TERMINATING RESISTOR
(ONE RESISTOR ON EACH END)
28 AC1 (MAKE NO CONNECTION)
27 AC2 (MAKE NO CONNECTION)
26 ^{ISO VCC1}
25 ^B
R7*
24 ^{ISO RO DRV}
23 ^A
22 ^{ISO DI IN}
21 ^{ISO DE IN}
R6*
R4*
20 ^{ISO COM1}
19 ^{ISO DI DRV}
R5*
18 ^{ISO VCC2}
17 ^{ISO DE DRV}
16 ^{ISO COM2}
15 ^{ISO RO LED}
ISOLATION
COMMON
B
120Ω
A
SH
SHIELD
(OPTIONAL)
R8
100Ω
NOTE: RESISTOR R8
PROTECTS THE MAX3480E
FROM TRANSIENT
CURRENTS BETWEEN
SHIELD AND A AND B.
Figure 11. Typical RS-485/RS-422 Network
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