LT3755/LT3755-1/LT3755-2 40VIN, 75VOUT LED Controllers FEATURESDESCRIPTION n 3000:1 True Color PWM™ Dimming The LT®3755, LT3755-1 and LT3755-2 are DC/DC control- n Wide Input Voltage Range: 4.5V to 40V lers designed to operate as a constant-current source for n Output Voltage Up to 75V driving high current LEDs. They drive a low side external n Constant-Current and Constant-Voltage Regulation N-channel power MOSFET from an internal regulated 7.15V n 100mV High Side Current Sense supply. The fixed frequency, current mode architecture n Drives LEDs in Boost, Buck Mode, Buck-Boost Mode, results in stable operation over a wide range of supply SEPIC or Flyback Topology and output voltages. A ground referenced voltage FB pin n Adjustable Frequency: 100kHz to 1MHz serves as the input for several LED protection features, n Open LED Protection and also makes it possible for the converter to operate n Programmable Undervoltage Lockout with Hysteresis as a constant-voltage source. A frequency adjust pin n Improved Open LED Status Pin (LT3755-2) allows the user to program the frequency from 100kHz n Frequency Synchronization (LT3755-1) to 1MHz to optimize efficiency, performance or external n PWM Disconnect Switch Driver component size. n CTRL Pin Provides Analog Dimming The LT3755/LT3755-1/LT3755-2 sense output current at n Low Shutdown Current: <1µA the high side of the LED string. High side current sensing n Programmable Soft-Start is the most flexible scheme for driving LEDs, allowing n Thermally Enhanced 16-Lead QFN (3mm × 3mm) boost, buck mode or buck-boost mode configuration. and MSOP Packages The PWM input provides LED dimming ratios of up to n AEC-Q100 Qualified For Automotive Applications 3000:1, and the CTRL input provides additional analog APPLICATIONS dimming capability. All registered trademarks and trademarks are the property of their respective owners. Protected by U.S. patents, including 7199560 and 7321203. n High Power LED n Battery Chargers n Accurate Current Limited Voltage Regulators TYPICAL APPLICATION50W White Automotive LED Headlamp DriverEfficiency vs VIN V 22µH IN 8V TO 100 40V 4.7µF 1M V 1M 4.7µF IN SHDN/UVLO FB 96 VREF 185k ISP 23.7k 332k LT3755-2 0.1Ω 1A CTRL 92 INTVCC 40.2k ISN GATE 100k 88 SENSE EFFICIENCY (%) OPENLED 0.015Ω 50W PWM LED SS 84 STRING RT PWMOUT VC GND INTVCC 0.01µF 28.7k 80 375kHz 0 10 20 30 40 10k 4.7µF VIN (V) 0.001µF 37551 TA01b 37551 TA01a Rev. E Document Feedback For more information www.analog.com 1 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Pin Configuration Order information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Package Description Revision History Typical Application Related Parts