可调LED亮度驱动电路设计

I亮度可调的LED驱动电路摘要LED亮度可调通过有两种可行方案：第一种通过单片机的占空比电压来输出不同的电压，从而实现设计要求；第二种通过单片机控制数模转换器来输出不同的电流，然后经过放大器来进行发大，从而实现输出不同的电压，来驱动LED。对于第一种方案，优点是设计简单，且使用的电子器件类较少，造价成本低，但是其集成度低，看起来较复杂，不适于现代人的思想要求。对于第二种方案，优点是集成度高，且设计图看起来明了，因为其集成度高，且使用了数模转换器，因此和第一种设计方案相比略高。所以本设计采用了第二种方案。本设计的结果是设计制作一种可手动和自动循环的led调光电路；自动调光时可使等在熄灭、微亮、较量及最亮四种状态中不断循环；实现灯光的循环调节功能(循环时间分别为为2s、4s、6s、8s、10s、12s)；关键词：LED，数模转换器，放大器，调光IIDrivingcircuitwithadjustablebrightnessLEDABSTRACTLEDbrightnesscanbeadjustedthroughhastwooptions:thefirstdutyratioofvoltagetooutputdifferentvoltagethroughtheMCU,inordertoachievethedesignrequirements;secondthroughthecontrolofthemicrocontrollerDACtodifferentoutputcurrent,andthenthroughtheamplifierisbigger,soastorealizetheoutputofdifferentvoltage,todriveLED.Inthefirstscheme,hastheadvantagesofsimpledesign,electronicdevicesandtheuseofsmall,lowcost,butitslowintegration,lookmorecomplex,notsuitablefortherequirementsofmodernthought.Inthesecondmethod,hastheadvantagesofhighintegration,anddesignlooksclear,becauseofitshighdegreeofintegration,andtheuseofadigital-to-analogconverter,andcomparedtothefirstdesignslightlyhigher.Sothesecondschemesareadoptedinthisdesign.TheresultofdesignistodesignakindofmanualandautomaticcycleLEDdimmingcircuit;automaticdimmingcanmakeintheextinction,shimmering,contestandthebrightestfourstatesrequirecontinuouscycle;circulationvelocityoflightcanbeadjusted(cycletimeare2S,4S,6S,8s,10s,12S);KEYWORDS:LED,DigitalAnalogConverter，Amplifier，DimingIII目录摘要.....................................................................IABSTRACT................................................................II1绪论....................................................................11.1选题背景..........................................................11.2选题背景概括......................................................11.3选题的目的及意义..................................................22元器件介绍..............................................................32.1LED灯的介绍......................................................32.1.1LED灯的发展史历史..........................................32.2单片机的介绍......................................................32.2.1单片机引脚..................................................42.3DAC0832..........................................................82.3.1引脚介绍....................................................82.3.2工作方式....................................................82.3.3采用DAC0809实现A/D转换....................................92.3.4输出形式...................................................102.3.5运算放大器................................................102.3.6由电阻网络和运算放大器构成的D/A转换器.....................112.3.7采用T型电阻网络的D/A转换器...............................112.3.8D/A转换器性能参数.........................................122.3.9DAC0832及接口电路.........................................122.3.10DAC0832的内部结构........................................132.3.11DAC0832引脚特性..........................................132.3.12DAC0832的工作方式........................................142.3.13DAC0832的应用举例........................................142.4LM324...........................................................142.4.1LM324的简介...............................................142.4.2同相交流放大器.............................................152.4.3反相交流放大器.............................................152.4.4交流信号三分配放大器.......................................162.4.5有源带通滤波器.............................................162.4.6单稳态触发器...............................................172.4.7比较器.....................................................173分部电路介绍...........................................................193.1开关控制电路.....................................................193.2复位电路.........................................................193.3单片机主控电路...................................................203.470832数模转换电路...............................................203.5放大电路.........................................................21IV4电路设计要求及方案选取.................................................224.1电路设计要求.....................................................224.2可行性方案列举..................................................224.3可行性方案分析...................................................225软件程序..............................................................237结果总结...............................................................26致谢...................................................................27参考文献.............................................................28附录Ⅰ元器件清单.......................................................29附录II设计总电路图.....................................................30亮度可调的LED驱动电路11绪论1.1选题背景上个世纪60年代，科技工作者利用半导体PN结发光的原理，研制成了LED发光二极管。当时研制的LED，所用的材料是GaASP，其发光颜色为红色[1]。经过近30年的发展，现在大家十分熟悉的LED，已能发出红、橙、黄、绿、蓝等多种色光。最初LED仅用作仪器仪表的指示光源，后来各种光色的LED在交通信号灯和大面积显示屏中得到了广泛应用，产生了很好的经济效益和社会效益。通常LED能直接发出红、黄、蓝、绿、青、橙、紫、白色的光，但对于一般照明而言，人们更需要白色的光源。经过多年研究，人们在1998年发白光的LED开发成功。这种LED是将GAN芯片和YAG（钇铝石榴石）封装在一起做成的。芯片GAN发蓝光，高温烧结制成的YAG荧光粉受此蓝光激发后发出黄色光射，峰值达550nm。蓝光LED基片安装在碗形反射腔中，覆盖以混有YAG的树脂薄层，约200-500nm。LED基片发出的蓝光部分被荧光粉吸收，另一部分蓝光与荧光粉发出的黄光混合，最终可以得到得白光。现在，对于白色LE