PIN FUNCTION
Pin 1 – RO – Receiver Output.
RO
RE
DE
DI
1
2
3
4
8
7
6
5
V
B
A
R
CC
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.
D
GND
Pin
6 – A – Driver Output/Receiver Input
SP485
Non-inverting.
Top View
Pin 7 – B – Driver Output/Receiver Input Inverting.
Pin 8 – Vcc – Positive Supply 4.75V<Vcc< 5.25V.
SP481E and SP485E
Pinout (Top View)
A
Test Point
CRL
1k
Receiver
Output
R
VCC
S1
S2
VOD
1k
VOC
R
B
Figure 1. RS-485 Driver DC Test Load Circuit
Figure 2. Receiver Timing Test Load Circuit
CL1
VCC
A
B
RDIFF
DI
A
B
500
RO
S1
S2
Output
Under
Test
CL
CL2
15pF
Figure 4. RS-485 Driver Timing Test Load #2 Circuit
Figure 3. RS-485 Driver/Receiver Timing Test Circuit
f = 1MHz; tR < 10ns; tF < 10ns
1.5V
+3V
0V
B
1.5V
DI
tPLH
tPHL
1/2VO
1/2VO
DRIVER
OUTPUT
VO
A
tDPLH
tDPHL
+
DIFFERENTIAL
OUTPUT
VO
0V
–
VO
VA – VB
tR
tF
tSKEW = tDPLH - DPHL
t
|
|
Figure 5. Driver Propagation Delays
Rev. 5/16/03
SP481E Low Power Half-Duplex RS485 Transceivers
© Copyright 2003 Sipex Corporation
4
SIPEX [ SIPEX CORPORATION ]
