3V
INPUT
0V
V
OH
Y OUTPUT
V
OL
t
PHL
V
OH
Z OUTPUT
V
OL
t
TD
t
TD
1.5V
t
PLH
V
OM
1.5V
t
PHL
V
OM
IN
1.5V
1.5V
3V
0V
t
DO1
t
DO2
2.0V
90%
50%
10%
-2.0V
t
PLH
V
OM
V
OM
OUT
50%
10%
90%
V
OM
= V
OH
+ V
OL
≈
1.5V
2
Figure 8. Driver Propagation Delay Waveforms
Figure 9. Driver Differential Output Delay and Transition
Time Waveforms
3V
DE
0V
V
OH
OUTPUT
HIGH
0V
V
CC
OUTPUT
LOW
V
OL
V
OM
= V
OH
+ V
OL
≈
1.5V
2
t
PZL
V
OM
t
PLZ
0.25V
t
PZH
V
OM
t
PHZ
0.25V
1.5V
1.5V
3V
INPUT
0V
t
RPLH
V
CC
OUTPUT
0V
V
OM
= V
CC
2
V
OM
V
OM
t
RPHL
1.5V
1.5V
Figure 10. Driver Enable and Disable Timing Waveforms
Figure 11. Receiver Propagation Delay Waveforms
S1 is open
S2 is closed
S3 = 1.5V
3V
RE
0V
t
PRHZ
V
OH
OUTPUT
0V
10%
1.5V
t
PRZH
t
PRSH
OUTPUT
V
OL
3V
S1 is closed
S2 is open
S3 = -1.5V
1.5V
1.5V
RE
0V
1.5V
t
PRLZ
V
CC
1.5V
t
PRZL
t
PRSL
1.5V
10%
Figure 12. Receiver Enable and Disable Waveforms
NOTE 1:
The input pulse is supplied by a generator with the following characteristics:
PRR=250KHz, 50% duty cycle, t
r
< 6.0ns, Z
0
=50Ω.
NOTE 2:
C
L
includes probe and stray capacitance.
10/15/02
SP3481/3485 Low Power Half-Duplex RS485 Transceivers
© Copyright 2000 Sipex Corporation
6
SIPEX [ SIPEX CORPORATION ]
