MAX1480 Maxim, MAX1480 Datasheet - Page 11

• Manufacturer Part Number: MAX1480
• Description: Complete / Isolated RS-485/RS-422 Data Interface
• Manufacturer: Maxim

The MAX1480A/MAX1480B/MAX1480C/MAX1490A/
MAX1490B typically withstand 1600V
2000V
from TTL/CMOS-logic with a series resistor, and the
received data output can directly drive TTL or CMOS-
logic families with only resistive pull-up.
Figure 1. MAX1480A/MAX1480B/MAX1480C Detailed Block Diagram and Typical Application Circuit
DE
RO
FS
DI
OR EQUIVALENT
RMS
74HC86
1.07MHz/
1.45MHz
OSC
V
5V
IN
(1 second). The logic inputs can be driven
RECEIVER OUTPUT
DRIVER ENABLE
DRIVER INPUT
V
C1
22 F
CC3
T F/F
Table 1. Pull-Up and LED Drive Resistors
______________________________________________________________________________________
Q
Q
MAX1480A
MAX1480B
MAX1480C
0.1 F
PART
C2
DE
DI
SD
´
´
R1
R2
R3
MAX845
Complete, Isolated RS-485/RS-422
LOGIC GROUND
R1 (Ω)
200
200
200
GND1
GND2
V
V
V
V
V
RMS
CC1
CC2
CC3
CC4
CC5
SD
RO
D1
D2
FS
DE
DI
GND1
N
N
10
11
12
13
14
1
2
3
4
5
6
7
8
9
(1 minute) or
D1
MAX845
D2
ISOLATION BARRIER
MAX1480A/B/C
R2 (Ω)
200
510
200
MAX1487
MAX487
R3 (Ω)
1000
3000
3000
28
27
26
25
24
23
22
21
20
19
18
17
16
ISO RO DRV
15
ISO DE IN
ISO DI IN
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 non-isolated side are low. Therefore, leave
DI
AC1 (MAKE NO CONNECTION)
AC2 (MAKE NO CONNECTION)
B
ISO RO DRV
A
ISO DE IN
ISO COM1
ISO DI DRV
ISO DE DRV
ISO COM2
ISO RO LED
ISO V
ISO DI IN
ISO V
´
CC1
CC2
and DE
R4 (Ω)
4300
2200
3000
ISOLATED COMMON
D
ISO COM1
´
ISO V
RE
R6
high or floating when in shutdown mode.
R
R4
R5 (Ω)
CC1
R5
MAX1480A: MAX1487
1000
3000
3000
MAX1480B: MAX487
MAX1480C: MAX487
Low-Power Shutdown Mode
SH
Data Interface
B
A
EXTERNAL RS-485/RS-422 WIRING
100
R6 (Ω)
R7
200
200
200
B
A
NOTE: RESISTOR R7 PROTECTS
(ONE RESISTOR ON EACH END)
TO OTHER TRANSCEIVERS
TO OTHER TRANSCEIVERS
THE MAX1480A/B/C FROM TRANSIENT
CURRENTS BETWEEN SHIELD AND
TRANSMISSION LINES.
TERMINATING RESISTOR
SHIELD (OPTIONAL)
SHIELD (OPTIONAL)
TWISTED PAIR
TWISTED PAIR
R
R
11
L
L