LTC1318
Single 5V
RS232/RS422/AppleTalk
®
DCE Transceiver
FEATURES
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DESCRIPTION
The LTC
®
1318 is a single 5V, RS232/RS422 transceiver
for connection to the DCE, or peripheral side of an interface
link. It includes an on-board charge pump to generate a
±8V
supply which allows true RS232 output swings. The
charge pump requires only four external 0.1µF capacitors.
The LTC1318 includes two RS232 drivers, a differential
RS422 driver, a dedicated RS232 receiver, and a pin
selectable RS232/RS422 receiver which can receive either
single-ended or differential signals.
The LTC1318 features driver outputs which can be taken
to common-mode voltages outside the power supply rails
without damage. Additionally, the driver outputs assume
a high impedance state when the power is shut off,
preventing externally applied signals from feeding back
into the power supplies. The RS232 devices will operate at
speeds up to 100kbaud. The RS422 devices will operate
up to 2Mbaud.
The LTC1318 is available in a 24-lead SO Wide package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
AppleTalk and LocalTalk are registered trademarks of Apple Computer, Inc.
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Single Chip Provides DCE RS232 or
RS422/AppleTalk DCE Port
Operates from a Single 5V Supply
Charge Pump Uses 0.1µF Capacitors
Output Common-Mode Voltage Range Exceeds
Power Supply Rails for All Drivers
Driver Outputs Are High Impedance with Power Off
Pin Selectable RS232/RS422 Receiver
Thermal Shutdown Protection
Drivers Are Short-Circuit Protected
APPLICATIONS
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Dual-Mode RS232/RS422 Peripherals
AppleTalk Peripherals
Single 5V Systems
TYPICAL APPLICATIONS
V
+
0.1µF
0.1µF
C1
+
C1
–
RXI1 RS232
RS232
LINES
TXO1 RS232
TXO2 RS232
5V
1k
22Ω
22Ω
V
CC
RXD
+
RXD
–
/RXI2
1k
APPLETALK
NETWORK
22Ω
22Ω
TXD
+
RS232
RS422
CHARGE
PUMP
V
–
C2
–
C2
+
RXO1
TXI1
TXI2
GND
RXDO/RXO2
TXD
RXMODE
GND
LTC1318
NC
LT1318 • TA01
0.1µF
0.1µF
TXD
(5V/DIV)
TO
DIGITAL
SYSTEM
TXD
+
, TXD
–
(2V/DIV)
RXDO
(5V/DIV)
TXD
–
RS422
22Ω
22Ω
NC
22Ω
LOCALTALK
®
TRANSFORMER
22Ω
100pF
×
4
U
U
U
Driver Output Waveforms
R
L
= 100Ω
C
L
= 100pF
200ns/DIV
1318 TA02
1
LINER [ LINEAR TECHNOLOGY ]
