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LTC1318

Single 5V

RS232/RS422/AppleTalk

®

DCE Transceiver

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Dual-Mode RS232/RS422 Peripherals

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AppleTalk Peripherals

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Single 5V Systems

The LTC

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 0.1

µF 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.

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Single Chip Provides DCE RS232 or

RS422/AppleTalk DCE Port

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Operates from a Single 5V Supply

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Charge Pump Uses 0.1

µF Capacitors

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Output Common-Mode Voltage Range Exceeds

Power Supply Rails for All Drivers

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Driver Outputs Are High Impedance with Power Off

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Pin Selectable RS232/RS422 Receiver

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Thermal Shutdown Protection

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Drivers Are Short-Circuit Protected

FEATURES

, LTC and LT are registered trademarks of Linear Technology Corporation.

AppleTalk and LocalTalk are registered trademarks of Apple Computer, Inc.

CHARGE

PUMP

RS232

LINES

APPLETALK

NETWORK

TRANSFORMER

100pF

× 4

22

Ω

22

Ω

22

Ω

22

Ω

22

Ω

22

Ω

22

Ω

22

Ω

RXI1

TXO1

TXO2

NC

RXO1

TXI1

TXI2

GND

RXDO/RXO2

TXD

RXMODE

GND

NC

0.1

µF

0.1

µF

0.1

µF

RS232

RS232

RS232

RS422

RS422

5V

1k

1k

0.1

µF

LTC1318

TO

DIGITAL

SYSTEM

LT1318 • TA01

RS232

200ns/DIV

1318 TA02

Driver Output Waveforms

TXD

(5V/DIV)

(2V/DIV)

RXDO

(5V/DIV)