LT1080/LT1081
U
W U U
APPLICATIO S I FOR ATIO
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.
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
(VCC; Pin 17) to zero for power-conscious systems.
LT1080/LT1081 Driver
Transceiver
LT1080 #1
DRIVER
LOGIC
TRANSMIT/RECEIVE
LINE
RS232
TRANSMIT/RECEIVE
LINE
30V
–30V
OUTPUT CAN
BE FORCED
EXTERNALLY
1080/81 F01
LT1080 #2
RECEIVER
Older RS232 Drivers and CMOS Drivers
+
V
LOGIC
INVERTER
WITH SOME DRIVERS,
EXTERNALLY APPLIED
VOLTAGE CAN FORCE
THE SUPPLIES
ON/OFF
(TRANSMIT/
RECEIVE)
INPUT
1080/81 F03
–
1080/81 F02
V
Sharing a Receiver Line
Sharing a Transmitter Line
LT1080 #1
RECEIVER
LT1080 #1
DRIVER
RS232
INPUT A
LOGIC
INPUT A
LT1080 #2
RECEIVER
LT1080 #2
DRIVER
RS232
TRANSMISSION
LINE
RS232
INPUT B
LOGIC
OUTPUT
LOGIC
INPUT B
LOGIC
INVERTER
LOGIC
INVERTER
ON/OFF
(CHANNEL
SELECT)
INPUT
ON/OFF
(CHANNEL
SELECT)
INPUT
1080/81 F04
1080/81 F05
10801fe
6
Linear [ Linear ]
