SP306 Sipex, SP306 Datasheet - Page 4

• Manufacturer Part Number: SP306
• Description: RS-422/RS-423 Line Drivers/Receivers
• Manufacturer: Sipex

92
and sink current capability. The RS423 line
drivers convert TTL logic levels into inverted
RS-423 output signals. All line drivers are inter-
nally protected against short circuits on their
outputs.
The RS-422 receivers convert the RS-422 dif-
ferential input signals into non–inverted TTL
logic levels. Receiver input thresholds are
input data up to 1Mbps. The RS-423 receivers
convert the RS-423 input signals into inverted
TTL output logic levels. The RS-423 receivers
have an input threshold of 200mV, and can
receive data up to 100kbps.
A loopback test mode is provided that puts the
driver outputs into a high impedance tri–state
level, and routes the driver outputs to their
associated receiver inputs. In this configuration,
Figure 1. Control Input Configuration — SELECT A = 0, SELECT B = 0
200mV. The RS-422 receivers can receive
LOOPBACK = 1
SELECT A = 0
SELECT B = 0
* Tri–state output
RS-423 DRIVER
R
R
T
T
OUT
IN
OUT
IN
A1
B1
A1
B1
14
22
8
7
+5V +12V –12V
28
V
GND
SELECT A
SELECT B
LOOPBACK
CC
SUPPLY
1
V
RS-423 RECEIVER
DD
SP306
15
V
EE
R
R
T
T
OUT
OUT
IN
IN
LOOPBACK = 0
A
B
SELECT A = 0
SELECT B = 0
A
B
the signal path is non–inverting from the TTL
driver inputs to the receiver TTL outputs. This
operating mode allows the controlling system to
perform diagnostic self–test of the RS-422/
RS-423 transceiver circuitry at speeds up to
3kbps.
APPLICATION INFORMATION
Control Logic Configuration
Software control of the SP306 is via two select
pins (7 and 8) and a loopback control pin (22).
SELECT A and SELECT B allow the user to
program the SP306 for four different interface
modes. Loopback mode can be selected in any
of these interface modes. The figures that follow
outline the various operating modes that are
supported by the SP306.
T
T
R
R
RS-422 RECEIVER
OUT
OUT
IN
IN
A1
B1
A*1
B*1
14
22
8
7
+5V +12V –12V
28
V
GND
SELECT A
SELECT B
LOOPBACK
CC
SUPPLY
1
V
DD
SP306
15
V
EE
* Tri–state output
RS-422 DRIVER
R
R
T
T
OUT
OUT
IN
IN
A
B
A
B
SIGNAL PROCESSING EXCELLENCE
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