Datasheet LT3744 (Analog Devices)

LT3744 High Current Synchronous Step-Down LED Driver
FeaTures DescripTion
n
Ideal for Driving Up to 40A LEDs
The LT®3744 is a fixed frequency synchronous step-down n
Up to 3000:1 PWM Dimming
DC/DC controller designed to drive a LED load at up to 20A n
20:1 Analog Dimming
continuous or 40A pulsed. The peak current mode controller n
±3% Current Regulation Accuracy
will maintain ±3% LED current regulation over a wide output n
±3% Voltage Regulation Accuracy
voltage range, from VEE to VIN. By allowing VEE to float n Unique Inverting Buck-Boost Topology Allows to negative voltages, several LEDs in series can be driven Grounded Heat Sink to Be Used for RGB LEDs from a single Li-Ion battery with a simple, single step-down n 3.3V to 36V Input Voltage Range output stage. PWM dimming is achieved with the PWM pins. n Peak Current Mode with DC LED Current Sensing The regulated LED current is set with analog voltages at the n Open and Shorted LED Protection and Fault Reporting CTRL pins. Regulated voltage and overvoltage protection n Floating LED Driver Allows Single Power Solution are set with a voltage divider from the output to the FB pin. to Drive Multicolor LEDs or Single LED with Three The switching frequency is programmable from 100kHz to Different Regulated Currents 1MHz through an external resistor on the RT pin. n Thermally Enhanced 5mm × 6mm QFN 36-Lead Additional features include an accurate external reference Package voltage, a control input for thermally derating regulation current, an accurate EN/UVLO pin, an open-drain output
applicaTions
fault flag, OVLO, frequency synchronization, and thermal n LED Driver for DLP Projectors shutdown. n Heads-Up Displays 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. n High Power LED Protected by U.S. Patents, including 7199560, 7321203, 8120335 and 8901904.
Typical applicaTion LED Driver for DLP Projectors LED Current Waveforms
V
(2000:1) 0A to 6.7A to 13.3A to 20A
EN/UVLO EN/UVLO IN VIN PWM1 20µF 220µF 3.3V TO 12V PWM2 PWM1 PWM3 VEE TG 5V/DIV CTRL1 220nF PWM2 CTRL2 BOOST CTRL3 5V/DIV SW PWM3 LT3744 2V 0.47µH 1mΩ 20A MAXIMUM 5V/DIV VREF INTVCC 2.2µF 22µF 330µF 100k 330µF I 45.3k FAULT BG LED 330µF 6.7A/DIV CTRLT VEE 51k ISP 680k SGND ISN GREEN 10µF SYNC PWM_OUT1 SS 3744 TA01b 1nF RT 25µsec/DIV PWM_OUT2 82.5k V VEE FNEG 4.7nF PWM_OUT3 51k VC1 LED_ISP 4.7nF LED_ISN 51k V FB 3mΩ C2 4.7nF 10k 51k VC3 3744 TA01a VEE 3744fa For more information www.linear.com/LT3744 1 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Package Description Typical Application Related Parts