Datasheet

Transformer Driver for
Isolated RS-485 Interface
C3
0.1μF
C1
0.1μF
C2
22μF
ISO 5V
ISOLATION
BARRIER
5V
V
IN
MAX253
D1
D2
FS
GND1 GND2
V
CC
1
8
6
27
3
1N5817
SD
4
ON / OFF
390Ω
*74HC04
DE
RO
390Ω
*74HC04
DI
3.3kΩ
1
3
5
4
6
1
2
4
3
5
4
1
3
6
*74HC04
*74HC04 OR EQUIVALENT
** SEE TABLE 2
MAX667
564
SHDNSET GND
MAX481
MAX483
MAX485
MAX487
52
RE GND
C4
22μF
IN OUT
82
1N5817
390Ω
4
3.3kΩ
3.3kΩ
3
1
8
6
7
DI
DE
RO
A
B
PC410 / 417
PC357T
PC410 / 417
1CT:1.3CT**
V
CC
485
I/O
Figure 3. Typical RS-485 Application Circuit, 5V Configuration
MAX253
Maxim Integrated
7