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Copyright © 1998

Rev. 0.4a ,2005-03-09

LX2172 / 73

DESCRI PTI O N

The

LX2172/73

are

fixed-frequency,

current-mode switching regulator integrated

circuits. These ICs contain all necessary

control circuitry plus a 1.25A on-board

transistor to design a complete DC:DC

switching regulator with minimum external

components.

All functions are integrated into a single

IC, available in 8-pin DIP and SOIC or a 5-

pin TO-220 power package, making them

extremely easy to design with and use. The

LX2172/73 are optimized for

boost and flyback applications, but can

also be used in forward and inverting

converter configuations.

The LX2172 can be connected to an

external clock for synchronization, and can

enter micropower operation when the VC

pin is pulled low. The LX2173 has an

enable function, which permits extremely

low micropower operation, consuming

under 10µA current when the ENABLE

pin is brought low

IMPORTANT: For the most current data, consult MICROSEMI’s website: http://www.microsemi.com

PRODUCT H I GHLIGHT

Input 6-24V, Output 7V, 300mA

L1

D1

E

2

V

C

FB

SYNC

GND

V

SW

E

1

V

IN

1mH

1

2

3

4

8

7

6

5

U1

100

3.0k

0.47 µF

(See Note 1)

13.7k

22µF

0.47 µF

1N5817

L2

1mH

220 µF

7V

Output

7V

300mA

0.1 µF

330 µF

Note 1: SYNC Pin Requirements:

A) F

B) TTL Compatible Level

C) Pulse Width T

KEY FEATUR ES

1.25A, 65V Internal Power

Switch

3V - 25V Input Voltage Range

Current-Mode Operation

Improved Internal Cycle-By-

Cycle Current Limiting

Thermal Shutdown

Less Than 10µA Quiescent

Current In Microprocessor

Shutdown Mode

External Frequency

Synchronization Possible

100kHz Operating Frequency

APPLI CATI ONS

Boost Converter

Laptop / Notebook Computers

Portable Equipment

Small Motor Applications

Flyback Converters

Part #

Pin 4 Connection

LX2172

SYNC Input

LX2173

Low µPower Mode

(Hi ENABLE)

PACKAGE ORDER INFO

M

Plastic DIP

8-Pin

DM

Plastic SOIC

8-Pin

P

Plastic TO-220

5-Pin

°C)

RoHS Compliant / Pb-free

Transition DC: 0503

RoHS Compliant / Pb-free

Transition DC: 0440

0 to 70

LX217xCM

LX217xCDM

LX217xCP

Note: Available in Tape & Reel. Append the letters “TR” to the part number. (i.e. LX2172CDM-TR)