LT3574



3574f

Features

applications

Description

Isolated Flyback Converter

Without an Opto-Coupler

cally designed for the isolated flyback topology. No third

winding or opto-isolator is required for regulation. The

part senses the isolated output voltage directly from the

primary side flyback waveform. A 0.65A, 60V NPN power

switch is integrated along with all control logic into a

16-lead MSOP package.

The LT3574 operates with input supply voltages from

3V to 40V, and can deliver output power up to 3W with

no external power switch. The LT3574 utilizes boundary

mode operation to provide a small magnetic solution with

improved load regulation.

The output voltage is easily set with two external resistors

andthetransformerturnsratio.Off-the-shelftransformers

are available for many applications.

5V Isolated Flyback Converter

n

3V to 40V Input Voltage Range

n

0.65A, 60V Integrated NPN Power Switch

n

Boundary Mode Operation

n

No Transformer Third Winding or

Opto-Isolator Required for Regulation

n

Improved Primary-Side Winding Feedback

Load Regulation

n

n

BIAS Pin for Internal Bias Supply and Power

NPN Driver

n

Programmable Soft-Start

n

Programmable Power Switch Current Limit

n

16-Lead MSOP Package

n

Industrial, Automotive and Medical Isolated

Power Supplies

Load Regulation

SHDN/UVLO

TC

SS

SW

VC

GND TEST BIAS

LT3574

3574 TA01

28.7k

10k

59k

12V TO 24V

5V

0.35A

3:1

357k

51.1k

•

•

10nF

1nF

6.04k

2k

80.6k

B340A

PMEG6010

0

–1.0

–0.5

0

0.5

1.0

100

200 300 400

3574 TA01b

500 600 700

typical application

L

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trademarks are the property of their respective owners.