LT3743 High Current Synchronous Step-Down LED Driver with Three-State Control FEATURESDESCRIPTION n PWM Dimming Provides Up to 3000:1 Dimming Ratio The LT®3743 is a fixed frequency synchronous step-down n CTRL_SEL Dimming Provides Up to 3000:1 Dimming DC/DC controller designed to drive high current LEDs. The Ratio Between Any Current average current mode controller will maintain inductor n Three-State Current Control for Color Mixing current regulation over a wide output voltage range of 0V n ±6% Current Regulation Accuracy to (VIN – 2V). LED dimming is achieved through analog n 6V to 36V Input Voltage Range dimming on the CTRL_L, CTRL_H and CTRL_T pins and n Average Current Mode Control with PWM dimming on the PWM and CTRL_SEL pins. n 2µs Maximum Recovery Time Between Any Current Through the use of externally switched load capacitors, Regulation State the LT3743 is capable of changing regulated LED current n <1µA Shutdown Current levels within several µs, providing accurate, high speed n Output Voltage Regulation and Open-LED Protection PWM dimming between two current levels. The switching n Thermally Enhanced 4mm × 5mm QFN and frequency is programmable from 200kHz to 1MHz through 28-Pin FE Package an external resistor on the RT pin. Additional features include voltage regulation and overvolt- APPLICATIONS age protection set with a voltage divider from the output to the FB pin. Overcurrent protection is provided and set n DLP Projectors by the CTRL_H pin. n High Power Architectural Lighting L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and n Laser Diodes 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, 7321203, 8120335 and 8901904. TYPICAL APPLICATION92% Efficient 20A LED Driver EN/UVLO EN/UVLO V V IN IN PWM PWM 4.7µF 10V TO 30V 1µF CTRL_SEL CTRL_SEL ×4 RT HG M1 CTRL_SEL 82.5k SYNC 220nF OUTPUT 5V/DIV CBOOT 1.1µH 2.5mΩ 20A MAXIMUM PWM VREF LT3743 SW 5V/DIV 2.2nF 4.7µF 100k CTRL_L VCC_INT 330µF SW 22µF ×3 20V/DIV RHOT 100k CTRL_H LG M2 499Ω 330µF GND ×3 CTRL_T SENSE+ M3 ILED SENSE– 10A/DIV RNTC PWMGH 10k M4 SS PWMGL 10nF 51.1k 20µs/DIV 3743 TA01b VIN = 24V 0A TO 2A TO 20A LED CURRENT STEP FB V 330µF CL VCH 10.0k 3743 TA01a ×3 34k 34k M1, M2: SiR462DP 8.2nF 8.2nF M3, M4: Si7234DP 3743fe For more information www.linear.com/LT3743 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 Revision History Typical Application Related Parts 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
