PIN FUNCTION
Pin ꢀ - RO - Receiver Output
Pin 2 - RE - Receiver Output Enable Active LOW
Pin 3 - DE - Driver Output Enable Active HIGH
Pin 4 DI - Driver Input
Pin 5 - GND - Ground Connection
Pin 6 - A - Driver Output / Receiver input
Non-Inverting
Pin 7 - B - Driver Output / Receiver Input Inverting
Pin 8 - Vcc - Positive Supply 4.75V ≤ Vcc ≤ 5.25V
TEST CIRCUITS
1kΩ
A
Test Point
1kΩ
Receiver
Output
V
CC
R
R
S
1
V
OD
C
RL
V
OC
S
2
B
Figure 1. RS-485 Driver DC Test Load Circuit
Figure 2. Receiver Timing Test Load Circuit
V
CC
CL1
S
1
A
A
500Ω
DI
RL
Output
Under
Test
RO
B
B
CL2
15pF
C
L
S
2
Figure 3. RS-485 Driver/Receiver Timing Test
Figure 4. Driver Timing Test Load #2 Circuit
f ≥1MHz; tR ≤10ns; tF ≤10ns
1.5V
+3V
1.5V
DRIVER INPUT
0V
tPLH
tPHL
B
1/2VO
1/2VO
DRIVER
OUTPUT
VO
A
tDPLH
tDPHL
+
VO
DIFFERENTIAL
OUTPUT
0V
–
VO
VA –VB
tF
tR
tSKEW= |tDPLH-tDPHL
|
Figure 5. Driver Propagation Delays
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 5ꢀ0-668-70ꢀ7 • www.exar.com
SP48ꢀE,485E_ꢀ00_ꢀ2ꢀ808
5
EXAR [ EXAR CORPORATION ]
