LT3756/LT3756-1/LT3756-2

1

Rev. C

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TYPICAL APPLICATION

FEATURES

APPLICATIONS

DESCRIPTION

LED Controller

TheLT®3756,LT3756-1andLT3756-2areDC/DCcontrol-

lers designed to operate as a constant-current source for

driving high current LEDs. They drive a low side external

N-channelpowerMOSFETfromaninternalregulated7.15V

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/LT3756-2 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.

94% Efficient 30W White LED Headlamp Driver

n

3000:1 True Color PWM™ Dimming

n

Wide Input Voltage Range: 6V to 100V

n

Output Voltage Up to 100V

n

Constant-Current and Constant-Voltage Regulation

n

100mV High Side Current Sense

n

Drives LEDs in Boost, Buck Mode, Buck-Boost Mode,

SEPIC or Flyback Topology

n

Adjustable Frequency: 100kHz to 1MHz

n

Open LED Protection

n

Programmable Undervoltage Lockout with Hysteresis

n

Improved Open LED Status Pin (LT3756-2)

n

Frequency Synchronization (LT3756-1)

n

PWM Disconnect Switch Driver

n

CTRL Pin Provides Analog Dimming

n

Low Shutdown Current: <1µA

n

Programmable Soft-Start

n

Thermally Enhanced 16-Lead QFN (3mm × 3mm)

and MSOP Packages

n

AEC-Q100 Qualified for Automotive Applications

n

High Power LED Applications

n

Current Limited Constant Voltage Applications

n

Battery Charging

LT3756-2

22µH

GND

SHDN/UVLO

FB

ISP

332k

100k

1M

4.7µF

0.001µF

0.01µF

8V TO 60V

(100V TRANSIENT)

185k

10k

28.7k

375kHz

1%

4.7µF

40.2k

CTRL

0.018

0.27

1M

14k

370mA

4.7µF

30W

LED

STRING

375612 TA01a

OPENLED

PWM

SS

RT

ISN

GATE

SENSE

PWMOUT

0

20

80

84

88

92

96

100

40

60

80

375612 TA01b

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