LT1081 LINER [Linear Technology], LT1081 Datasheet - Page 6

• Manufacturer Part Number: LT1081
• Description: Advanced Low Power 5V RS232 Dual Driver/Receiver
• Manufacturer: LINER [Linear Technology]

APPLICATIO S I FOR ATIO
LT1080/LT1081
The driver output stage of the LT1080 offers significantly
improved protection over older bipolar and CMOS de-
signs. In addition to current limiting, the driver output can
be externally forced to 30V with no damage or excessive
current flow, and will not disrupt the supplies. Some
drivers have diodes connected between the outputs and
the supplies, so externally applied voltages can cause
excessive supply voltage to develop.
6
(CHANNEL
SELECT)
INPUT A
INPUT B
Older RS232 Drivers and CMOS Drivers
ON/OFF
RS232
RS232
INPUT
Sharing a Receiver Line
LT1080/LT1081 Driver
U
U
V
V
LT1080 #1
RECEIVER
LT1080 #2
RECEIVER
+
–
LOGIC
INVERTER
OUTPUT CAN
EXTERNALLY
WITH SOME DRIVERS,
EXTERNALLY APPLIED
VOLTAGE CAN FORCE
THE SUPPLIES
BE FORCED
1080/81 F01
W
1080/81 F04
–30V
30V
1080/81 F02
LOGIC
OUTPUT
U
Placing the LT1080 in the SHUTDOWN mode (Pin 18 low)
puts both the driver and receiver outputs in a high imped-
ance state. This allows data line sharing and transceiver
applications.
The SHUTDOWN mode also drops input supply current
(V
CC
TRANSMIT/RECEIVE
; Pin 17) to zero for power-conscious systems.
(CHANNEL
(TRANSMIT/
SELECT)
INPUT A
INPUT B
ON/OFF
RECEIVE)
LOGIC
LOGIC
INPUT
ON/OFF
LOGIC
INPUT
LINE
Sharing a Transmitter Line
LT1080 #2
RECEIVER
Transceiver
LT1080 #1
DRIVER
LT1080 #2
DRIVER
LOGIC
INVERTER
LOGIC
INVERTER
LT1080 #1
DRIVER
1080/81 F05
1080/81 F03
RS232
TRANSMISSION
LINE
RS232
TRANSMIT/RECEIVE
LINE