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LT1237

5V RS232 Transceiver with

Advanced Power Management and

One Receiver Active in Shutdown

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One Receiver Remains Active While in Shutdown

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ESD Protection over

±15kV

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Uses Small Capacitors: 0.1

µF, 0.2µF, 1.0µF

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60

µA Supply Current in Shutdown

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Pin Compatible with LT1137A

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Operates to 120kBaud

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CMOS Comparable Low Power 30mW

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Operates from a Single 5V Supply

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Easy PC Layout—Flowthrough Architecture

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Rugged Bipolar Design

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Outputs Assume a High Impedance State When Off

or Powered Down

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Absolutely No Latchup

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Available in SO and SSOP Packages

The LT

receiver RS232 transceiver. Included on the chip is a

shutdown pin for reducing supply current near zero.

During shutdown one receiver remains active to detect

incoming RS232 signals, for example, to wake up a

system.

The LT1237 is fully compliant with all EIA RS232 specifi-

cations. New ESD structures on the chip allow the LT1237

to survive multiple

±15kV strikes, eliminating the need for

costly TransZorbs

The LT1237 operates in excess of 120kbaud even driving

heavy capacitive loads. Two shutdown modes allow the

driver outputs to be shut down separately from the receiv-

ers for more versatile control of the RS232 interface.

During shutdown, drivers and receivers assume a high

impedance state.

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Notebook Computers

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Palmtop Computers

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

TransZorb is a registered trademark of General Instruments, GSI

Output Waveforms

R

1237 TA02

RECEIVER

OUTPUT

INPUT

DRIVER

OUTPUT

LT1237 TA01

1.0

µF

2

× 0.1µF

0.1

µF

TO

LINE

LT1237

1

2

3

4

5

6

7

8

9

10

11

12

13

14

DRIVER 1 OUT

RX1 IN

DRIVER 2 OUT

RX2 IN

RX3 IN

RX4 IN

DRIVER 3 OUT

RX5 IN (LOW-Q)

ON/OFF

28

27

26

25

24

23

22

21

20

19

18

17

16

15

2

× 0.1µF

DRIVER 1 IN

RX1 OUT

DRIVER 2 IN

RX2 OUT

RX3 OUT

RX4 OUT

DRIVER 3 IN

RX5 OUT (LOW-Q)

GND

DRIVER

DISABLE

RING DETECT IN

SHUTDOWN

CONTROL OUT

µCONTROLLER OR

µPROCESSOR

TO LOGIC

FEATURES

DESCRIPTIO

APPLICATIO S

TYPICAL APPLICATIO