Datasheet
MAX1480A/B/C, MAX1490A/B
Complete, Isolated RS-485/RS-422
Data Interface
12 ______________________________________________________________________________________
The MAX1480A/MAX1480B/MAX1480C/MAX1490A/
MAX1490B typically withstand 1600V
RMS
(1 minute) or
2000V
RMS
(1 second). The logic inputs can be driven
from TTL/CMOS-logic with a series resistor, and the
received data output can directly drive TTL or CMOS-
logic families with only resistive pullup.
Low-Power Shutdown Mode
The SD pin shuts down the oscillator on the internal power
driver. With the primary side in shutdown, no power is
transferred across the isolation barrier. The DI and DE
optocouplers, however, still consume current if the drive
signals on the nonisolated side are low. Therefore, leave
DI´ and DE´ high or floating when in shutdown mode.
AC1 (MAKE NO CONNECTION)
AC2 (MAKE NO CONNECTION)
SHIELD (OPTIONAL)
EXTERNAL RS-485/RS-422 WIRING
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
GND2
DE
V
CC4
DI
ISO COM2
ISO RO LED
V
CC5
RO
R
L
R
L
R4
R5
R7
100Ω
R1
R2
R3
R6
DE
´
DI´
V
IN
5V
22μF 0.1μF
C1 C2
MAX1480A/B/C
LOGIC GROUND ISOLATION BARRIER ISOLATED COMMON
DRIVER INPUT
DRIVER ENABLE
RECEIVER OUTPUT
DE
DI
RO
74HC86
OR EQUIVALENT
MAX1487
MAX487
MAX845
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
MAX845
N
MAX1480A: MAX1487
MAX1480B: MAX487
MAX1480C: MAX487
RE
ISO RO DRV
ISO DE IN
ISO DI IN
ISO COM1
ISO V
CC1
A
B
R
D
N
Q
Q
T F/F
V
CC3
FS
OSC
1.07MHz/
1.45MHz
SD
GND1
D2
D1
SHIELD (OPTIONAL)
NOTE: RESISTOR R7 PROTECTS
THE MAX1480A/B/C FROM TRANSIENT
CURRENTS BETWEEN SHIELD AND
TRANSMISSION LINES.
TWISTED PAIR
TO OTHER TRANSCEIVERS
TERMINATING RESISTOR
(ONE RESISTOR ON EACH END)
TWISTED PAIR
TO OTHER TRANSCEIVERS
Figure 1. MAX1480A/MAX1480B/MAX1480C Detailed Block Diagram and Typical Application Circuit
200
510
R2 (Ω)
4300
2200
R4 (Ω)
1000
3000
R3 (Ω)
200
200
R6 (Ω)
1000
3000
R5 (Ω)
200MAX1480A
200MAX1480B
R1 (Ω)PART
Table 1. Pull-Up and LED Drive Resistors
200 30003000 2003000200MAX1480C