Linear 公司的LT3743具有三态控制的大电流20A效率92% LED驱动器,采用平均电流模式控制,PWM调光高达3000:1,电流调整精度6%,输入电压6V-36V,关断电流小于1uA,具有输出电压调整和led开路保护特性.主要应用在DLP投映仪,大功率建筑照明和激光二极管.本文介绍了LT3743主要特性,方框图,以及典型应用电路,包括带分流输出的12V 20A LED驱动电路和16-36V 2A LED驱动电路, 12V5A 锂电子充电电路和24V 20A 3-LED驱动电路.

LT3743: 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 CTRL_L, CTRL_H and CTRL_T pins and with PWM dimming on the PWM and CTRL_SEL 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 CTRL_H pin.

LT3743主要特性:

PWM Dimming Provides Up to 3000:1 Dimming Ratio

CTRL_SEL 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 4mmx ?5mm QFN and 28-Pin FE Package

LT3743应用:

DLP Projectors

High Power Architectural Lighting

Laser Diodes


图1.LT3743方框图

图2.LT3743典型应用电路

图3.LT3743 12V 20A LED驱动电路(带分流输出)

图4.LT3743 16-36V 2A LED驱动电路(带分流输出)


图5.LT3743 13-36V 2A LED驱动电路(带限流分流输出)


图6.LT3743 13-30V 20A LED驱动电路(带开关阴极)


图7.LT3743 12V5A 锂电子充电电路

图8.LT3743 24V 20A 3-LED驱动电路

详情请见:
http://cds.linear.com/docs/Datasheet/3743p.pdf