LT1039-16_15 Datasheet, PDF (6/12 Pages) Linear Technology – RS232 Driver/Receiver with Shutdown

LT1039/LT1039-16
APPLICATIONS INFORMATION
The driver output stage of the LT1039 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.
LT1039 Driver
Sharing a Receiver Line
RS232
INPUT A
LT1039 #1
RECEIVER
LT1039
OUTPUT CAN
BE FORCED
EXTERNALLY
30V
– 30V
1039 AI01
Some drivers have diodes connected between the out-
puts and the supplies, so externally applied voltages can
cause excessive supply voltage to develop
Older RS232 Drivers and Other CMOS Drivers
RS232
INPUT B
ON/OFF
(CHANNEL SELECT)
INPUT
LT1039 #2
RECEIVER
LOGIC
INVERTER
1039 AI04
Transceiver
LOGIC
OUTPUT
V⁺
WITH SOME DRIVERS,
EXTERNALLY APPLIED
VOLTAGE CAN FORCE
THE SUPPLIES
V^–
1039 AI02
Placing the LT1039 in the shutdown mode (Pin 17 low)
puts both the driver and receiver outputs in a high imped-
ance state. This allows data line sharing and transceiver
applications.
Sharing a Transmitter Line
LOGIC
INPUT A
LT1039 #1
DRIVER
LOGIC
TRANSMIT/RECEIVE
LINE
LT1039 #1
DRIVER
RS232
TRANSMIT/RECEIVE
LINE
LT1039 #2
RECEIVER
ON/OFF
(TRANSMIT/RECEIVE)
INPUT
LOGIC
INVERTER
1039 AI05
The shutdown mode also drops all supply currents (V_CC,
V ⁺, V ^–) to zero for power conscious systems.
LOGIC
INPUT B
ON/OFF
(CHANNEL SELECT)
INPUT
6
LT1039 #2
DRIVER
LOGIC
INVERTER
1039 AI03
RS232
TRANSMISSION
LINE
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