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LT1537

Advanced Low Power

5V RS232 Transceiver with

Small Capacitors

DESCRIPTIO

S

FEATURE

The LT

ceiver, pin compatible with the LT1137A, offering perfor-

mance improvements and two shutdown modes. The

LT1537’s charge pump is designed for extended compli-

ance and can deliver over 35mA of load current. Supply

current is typically 8mA, competitive with similar CMOS

devices. An advanced driver output stage operates up to

250kbaud while driving heavy capacitive loads.

The LT1537 is fully compliant with all RS232 specifica-

tions. Special bipolar construction techniques protect the

drivers and receivers beyond the fault conditions stipu-

lated for RS232. Driver outputs and receiver inputs can be

shorted to

±25V without damaging the device or the

power supply generator. In addition, the RS232 I/O pins

are resilient to multiple

±5kV ESD strikes.

The transceiver has two shutdown modes. One mode

disables the drivers and the charge pump, the other shuts

down all circuitry. While shut down, the drivers and

receivers assume high impedance output states.

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

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Low Cost

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Uses Small Capacitors: 0.1

µF, 0.2µF

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1

s

s

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CMOS Comparable Low Power: 40mW

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Operates from a Single 5V Supply

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Easy PC Layout: Flow-through 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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Improved Protection: RS232 I/O Lines Can Be Forced

to

±25V Without Damage

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Output Overvoltage Does Not Force Current Back

into Supplies

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Absolutely No Latch-Up

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Available in SO Package

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APPLICATI

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Notebook Computers

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Palmtop Computers

APPLICATI

TYPICAL

R

LT1537 • TA02

LT1537 • TA01

0.1

µF

2

× 0.1µF

0.1

µF

TO

LINE

LT1537

1

2

3

4

5

6

7

8

9

10

11

12

13

14

DRIVER OUT

RX IN

DRIVER OUT

RX IN

RX IN

RX IN

DRIVER OUT

RX IN

28

27

26

25

24

23

22

21

20

19

18

17

16

15

2

× 0.1µF

DRIVER IN

RX OUT

DRIVER IN

RX OUT

RX OUT

RX OUT

DRIVER IN

RX OUT

+

TO LOGIC

ON/OFF = 5V

+

DRIVER

DISABLE

GND

INPUT

DRIVER

OUTPUT

RECEIVER

OUTPUT

Output Waveforms