LT3743

1

3743f

TYPICAL APPLICATION

DESCRIPTION

High Current Synchronous

Step-Down LED Driver with

Three-State Control

The LT

DC/DC controller designed to drive high current LEDs. The

average current mode controller will maintain inductor

current regulation over a wide output voltage range of 0V

dimming on the CTRL_L, CTRL_H and CTRL_T pins and

with PWM dimming on the PWM and CTRL_SEL pins.

Through the use of externally switched load capacitors,

the LT3743 is capable of changing regulated LED current

levels within several μs, providing accurate, high speed

PWM dimming between two current levels. The switching

frequency is programmable from 200kHz to 1MHz through

an external resistor on the RT pin.

Additional features include voltage regulation and

overvoltage protection set with a voltage divider from the

output to the FB pin. Overcurrent protection is provided

and set by the CTRL_H pin.

92% Efficient 20A LED Driver

FEATURES

APPLICATIONS

Ratio Between Any Current

Regulation State

× 5mm QFN and

28-Pin FE Package

EN/UVLO

PWM

CTRL_SEL

EN/UVLO

PWM

CTRL_SEL

HG

CBOOT

CTRL_L

CTRL_H

CTRL_T

LT3743

RT

SYNC

SW

LG

GND

VCH

VCL

PWMGH

PWMGL

220nF

1.1μH

20μF

1mF

2.5mΩ

FB

10nF

34k

9nF

34k

9nF

82.5k

40k

40k

1mF

51k

3743 TA01a

10.0k

20μF

1mF

2nF

680k

4.7μF

4

10V TO 36V

20A MAXIMUM

1μF

SS

45.3k

CTRL_SEL

5V/DIV

PWM

5V/DIV

SW

20V/DIV

10A/DIV

20μs/DIV

3743 TA01b

0A TO 2A TO 20A LED CURRENT STEP

L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear

Technology Corporation. All other trademarks are the property of their respective owners.

Protected by U.S. Patents including 7199560, 7321203 and others pending.