ADI LT3950 60V 1．5A LED驱动器解决方案

ADI公司的LT3950是60V 1.5A 多拓扑DC/DC转换器,特别设计用来驱动大电流LED.它包含一个1.5A 60V DMOS开关,支持外部PWM调光PMOS.LT3950具有用来调光的内部PWM发生器,把模拟控制信号转变指数标度,用来定义PWM调光占空比.采用指数标度来定义占空比保留了大范围LED电流的调光分辨率.除了恒流源工作模式,LT3950还提供输出电压调整,这可防止LED开路时所带来的危险性.可编程的开关频率在设计高效或降低元件尺寸时提供了灵活性.器件采用扩频调制降低了EMI.开关频率由驱动SYNC/SPRD引脚很容易和外部时钟同步.LED电流通过外接检测电阻进行编程. LT3950工作在升压,SEPIC,降压和降压-升压模式.128:1内部指数标度PWM调光,输入电压从3V到60V,100Hz时20000:1外部PWM调光,±2% LED电流和输出电压调整.主要用在显示器背光,汽车和航空照明.本文介绍了LT3950主要特性,框图和多种应用电路,演示板DC2788A主要指标,电路图, 测试程序建立图和材料清单.

The LT®3950 is a multitopology DC/DC converter designedspecifically to drive high current LEDs. It contains a 1.5A,60V DMOS switch and supports an external PWM dimmingPMOS. The LT3950 has an internal PWM generatorfor dimming that maps an analog control signal to anexponential scale used to define PWM dimming duty ratio.

Using an exponential scale to define duty ratio preservesdimming resolution across a wide range of LED current.In addition to operating as a constant current source, the

LT3950 also provides output voltage regulation. This canbe used to prevent damage to the part in case of open LEDevents. A programmable switching frequency offers flexibility

in design for higher efficiency or reduced componentsize. Enabling spread spectrum frequency modulationreduces EMI. The switching frequency can also easilybe synchronized by driving the SYNC/SPRD pin with anexternal clock. LED current is programmed with a singleexternal sense resistor and can be adjusted from zero tofull-scale by an analog signal at the CTRL pin.

LT3950主要特性:

nOperates in Boost, SEPIC, Buck Mode and Buck-Boost Mode

n128:1 Internal Exponential Scale PWM Dimming