High Current Synchronous Step-Down LED Driver with Three-State Control

The LT3743 is a fixed frequency synchronous step-down DC/DC controller designed to drive high current LEDs. The average current mode controller will maintain inductor current regulation over a wide output voltage range of 0V to (VIN – 2V). LED dimming is achieved through analog dimming on the CTRLL, CTRLH and CTRLT pins and with PWM dimming on the PWM and CTRLSEL pins. Through the use of externally switched load capacitors, the LT3743 is capable of changing regulated LED current levels within several μs, providing accurate, high speed PWM dimming between two current levels. The switching frequency is programmable from 200kHz to 1MHz through an external resistor on the RT pin.

Additional features include voltage regulation and overvoltage protection set with a voltage divider from the output to the FB pin. Overcurrent protection is provided and set by the CTRLH pin.

Applications

* DLP Projectors

* High Power Architectural Lighting

* Laser Diodes

* PWM Dimming Provides Up to 3000:1 Dimming Ratio

* CTRLSEL Dimming Provides Up to 3000:1 Dimming Ratio Between Any Current

* Three-State Current Control for Color Mixing

* ±6% Current Regulation Accuracy

* 6V to 36V Input Voltage Range

* Average Current Mode Control

* 2μs Maximum Recovery Time Between Any Current Regulation State

* <1μA Shutdown Current

* Output Voltage Regulation and Open-LED Protection

* Thermally Enhanced 4mm × 5mm QFN and 28-Pin FE Package