
M
Complete, Isolated RS-485/RS-422
Data Interface
14
______________________________________________________________________________________
Figure 4. Driver DC Test Load
R
R
V
OD
V
OC
D
Figure 5. Driver/Receiver Timing Test Circuit
DI
′
C
L1
(DE
′
)
C
L2
RO (RO)*
R
DIFF
V
ID
ISOLATION BARRIER
( ) ARE FOR
THE MAX1480A/B/C
* OPTOCOUPLER
OUTPUTS. SEE FIGURES 1
AND 2 FOR DETAILED BLOCK
DIAGRAM AND TYPICAL
APPLICATION CIRCUIT.
ISOLATION BARRIER
R
D
Test Circuits
28
27
26
25
24
23
22
21
1
2
3
4
5
6
7
8
AC1
V
IN
5V
SHUTDOWN
Si943304
DI
GND
DE
R1
R2
R3
P
RO
AC2
ISO V
CC1
B
D2
D1
V
CC2
V
CC1
ISO RO DRV
A
ISO DI IN
ISO DE IN
V
CC3
SD
FS
GND1
20
19
18
17
9
10
11
12
ISO COM1
ISO DI DRV
ISO V
CC2
ISO DE DRV
GND2
DE
V
CC4
DI
16
15
13
14
ISO COM2
ISO RO LED
V
CC5
RO
MAX1487
MAX845
ISOLATION BARRIER
MAX1480A
Figure 3. MAX1480A Low-Power Shutdown Mode