[原创] Linear LT3744大电流同步降压LED驱动方案

Linear公司的LT3744是固定频率大电流同步降压DC/DC控制器,LED驱动连续电流高达20A,脉冲电流40A,PWM调光3000：1,模拟调光20：1,输入电压3.3V到36V,主要用在DLP投映仪LED驱动器,智能显示器和大功率LED.本文介绍了LT3744主要特性,框图,多种应用电路,以及演示板2339A主要特性,电路图,材料清和PCB元件布局图.

The LT®3744 is a fixed frequency synchronous step-downDC/DC controller designed to drive a LED load at up to 20Acontinuous or 40A pulsed. The peak current mode controller will maintain ±3% LED current regulation over a wide outputvoltage range, from VEE to VIN. By allowing VEE to floatto negative voltages, several LEDs in series can be drivenfrom a single Li-Ion battery with a simple, single step-downoutput stage. PWM dimming is achieved with the PWM pins.The regulated LED current is set with analog voltages at theCTRL pins. Regulated voltage and overvoltage protectionare set with a voltage divider from the output to the FB pin.

The switching frequency is programmable from 100kHz to1MHz through an external resistor on the RT pin.

Additional features include an accurate external referencevoltage, a control input for thermally derating regulationcurrent, an accurate EN/UVLO pin, an open-drain outputfault flag, OVLO, frequency synchronization, and thermalshutdown.
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