LT3756/LT3756-1

1

37561f

TYPICAL APPLICATION

FEATURES

APPLICATIONS

DESCRIPTION

LED Controller

The LT

to operate as a constant-current source for driving high

current LEDs. They drive a low side external N-channel

power MOSFET from an internal regulated 7V supply. The

fixed frequency, current-mode architecture results in stable

operation over a wide range of supply and output voltages.

A ground referenced voltage FB pin serves as the input for

several LED protection features, and also makes it possible

for the converter to operate as a constant-voltage source.

A frequency adjust pin allows the user to program the

frequency from 100kHz to 1MHz to optimize efficiency,

performance or external component size.

The LT3756/LT3756-1 sense output current at the high

side of the LED string. High side current sensing is the

most flexible scheme for driving LEDs, allowing boost,

buck mode or buck-boost mode configuration. The PWM

input provides LED dimming ratios of up to 3000:1, and the

CTRL input provides additional analog dimming capability.

Both parts are available in the 16-lead QFN (3mm

× 3mm)

and MSOP packages.

94% Efficient 30W White LED Headlamp Driver

SEPIC or Flyback Topology

× 3mm)

and MSOP Packages

LT3756

22μH

GND

SHDN/UVLO

FB

ISP

332k

100k

1M

4.7μF

0.001μF

0.01μF

8V TO 60V

(100V TRANSIENT)

10k

332k

10k

28.7k

400kHz

1%

4.7μF

40.2k

CTRL

0.018Ω

0.27Ω

1M

14k

370mA

4.7μF

30W

LED

STRING

3756 TA01a

OPENLED

PWM

SS

ISN

GATE

SENSE

PWMOUT

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

True Color PWM is a trademark of Linear Technology Corporation. All other trademarks are

the property of their respective owners. Protected by U.S. Patents, including 7199560

and 7321203.

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37561 TA01b