Half-Duplex RS-485-/RS-422-Compatible
Transceiver with AutoDirection Control
Test Circuits and Waveforms
A
R
L
R
DIFF
2
A
B
DI
V
CC
V
ID
C
L
GND
V
OD
C
L
R
L
R
DIFF
V
OC
2
B
Figure 2. Driver-Timing Test Circuit
Figure 1. Driver DC Test Load
RE = V
f = 1MHz, t ≤ 3ns, t ≤ 3ns
LH HL
CC
V
CC
0
1.5V
1.5V
DI
1/2 V
O
t
t
DPHL
DPLH
B
A
V
O
1/2 V
RO
O
t
, t
DDD RED
(RO PULLED LOW)
O
V
= V(A) - V(B)
DIFF
V
O
90%
90%
V
DIFF
0
10%
10%
LH
-V
O
t
HL
t
Figure 3. Driver Propagation Delays
8
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