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LT1332

Wide Supply Range

Low Power RS232 Transceiver with

12V VPP Output for Flash Memory

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FEATURE

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Generates Full RS232 Signal Levels from 3V Supply

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12V VPP Output Available for Flash Memory

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Useful with a Wide Variety of Switching Regulators

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Wide Supply Range: 2V

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ESD Protection Over

±10kV

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Operates to 120k Baud

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Outputs Assume a High Impedance State When Off

or Powered Down

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One

µPower Receiver Remains Active While in

SHUTDOWN

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Flowthrough Architecture Eases PC Board Layout

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40

µA Supply Current in SHUTDOWN

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Absolutely No Latch-Up

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Available in SO and SSOP Packages

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APPLICATI

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Notebook and Palmtop Computers

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Mouse Driver Circuits

DESCRIPTIO

The LT1332 is a 3-driver/5-receiver RS232 transceiver,

designed to be used in conjunction with a switching

regulator. The LT1332 shares the regulator’s positive

output, while charge is capacitively pumped from the

regulator’s switch pin to the negative supply. Schottky

rectifiers built into the LT1332 simplify the charge

pump design.

The LT1332/LT1109A combination shown below gener-

ates fully compliant RS232 signal levels from as little as 2V

of input supply. The switcher can deliver greater than

100mA of output current, making the LT1332 an excellent

choice for mouse driver circuits.

Advanced driver output stages operate up to 120k baud

while driving heavy capacitive loads. New ESD structures

on chip make the LT1332 resilient to multiple

±10kV

strikes, eliminating costly transient suppressors.

A shutdown pin disables the transceiver except for one

receiver which remains active for detecting incoming

RS232 signals. When shut down, the disabled drivers and

receivers assume high impedance output states.

APPLICATI

TYPICAL

LT1332 • TA01

22

µF*

LT1332

1

2

3

4

5

6

7

8

9

10

11

12

24

23

22

21

20

19

18

17

16

15

14

13

SWITCHER

BATTERIES

UP TO 6V

1

µF

10

µF

12V VPP

OUTPUT

22

µF*

STANDARD FLASH MEMORY VPP GENERATOR

L1**

33

µH

0.1

µF

3V

RS232

ON/OFF

RS232

ON/OFF

RS232

SIDE

LOGIC

SIDE

NC

+

LT1109A-12

SW

ON/OFF

SENSE

GND

PGND

SW

*

**

AVX TAJE226K035

SUMIDA CD54-330N (708-956-0666)

MBRS130T3

LT1332 Powered from an LT1109A Micropower Switching Regulator

Configured for Flash Memory

Output Waveforms

DRIVER

OUTPUT

RECEIVER

OUTPUT

LT1332 • TA02

DRIVER

INPUT