毕业论文基于单片机简易数控直流电压源的设计

I摘要本设计以AT89S52单片机为核心控制芯片，实现数控直流电源功能的方案。设计采用8位精度的DA转换器DAC0832、三端可调稳压器LM350和一个UA741运算放大器构成稳压源，实现了输出电压范围为＋1.4V～+9.9V，电压步进0.1V的数控稳压电源，最大纹波只有10mV，具有较高的精度与稳定性。另外该方案只采用了5个按键实现输出电压的方便设定，具有设定值调整，微调（步进量0.1），粗调（步进量1）三种调整功能，显示部分我们采用了三位一体的数码管来显示输出电压值。我们自行设计了12V和5V电源为系统供电。该电路的原理是通过MCU控制DA的输出电压大小，通过放大器放大，放大后的电压作为LM350的参考电压，真正的电压还是由电压模块LM350输出。利用5个按钮调整电压、并且通过共阴极三位一体LED显示输出的电压值。设计使用3三位一体数码管，可以显示三位数，一个小数位，比如可以显示5.90V，采用动态扫描驱动方式。与传统的稳压电源相比具有操作方便，电源稳定性高以及其输出电压大小采用数码显示的特点。关键词：数控，步进，三端可调稳压器IIABSTRACTThedesigniswiththeMCUAT89S52forthecorecontrolchip,whichcarryouttheprojectthatthefunctionofthenumbercontrolsthedirectcurrentpowersupply.DesignedwiththeprecisionofeightDAconverterDAC0832,three-adjustableregulatorsLM350andaUA741OperationalAmplifiersconstituteRegulatorssource,theoutputvoltagerangeof+1.4V~+9.9V,0.1VvoltagestepNCRegulatorsPower,ithaswithhighprecisionandstabilityandonlyhavethebiggestrippleof10mV.Meanwhile,theprogramusedonlyfivekeystoachievetheconvenienceoftheoutputvoltagesetting,withsettingvalueadjustments.Ithasthreekindsofadjustfunction,whichcancarryoutmicro-adjustment(Steppingvolume0.1)andthecoarseadjustment(Steppingvolume1).Theshowpartwehaveadoptedathree-dimensionaldigitalpipetoshowtheoutputvoltagevalue.Andwedesignedthe12Vand5Vpowersupplysystemforelectricity.TheprincipleofthatelectriccircuitwasthattheoutputvoltagesizewhichpassestheMCUtocontrolDA,passingtheamplifieramplification,andthevoltageisthereferencevoltageoftheLM350.AndtherealvoltageisstilltheLM350outputsarefromthevoltagemoldpiece.Makinguseoffivebuttonstoadjustmentvoltages,andpassthetotalcathodeChristianTrinityLEDtodisplaytheoutput'svoltage.InthisdesignIused3piececodetubes,whichcanshowthreepositionnumbers,oneofthemisafractionposition.forexample,itcanshowa5.90Vs.InthisdesignIadoptthescantodrivewayisdynamicstatesweep.Withtraditionalsteadypresspowersupplytocomparetohaveanoperationconvenience,thepowersupplystabilityhighcharacteristics,itsexportationelectricvoltagesizeadoptionfiguresshow.Keywords:NumericalControl,Stepping,Three-adjustableregulatorsIII目录第1章绪论············································································11.1研究背景及意义··············································································11.2国内外研究状况··············································································11.3课题研究方法·················································································2第2章数控电压源的总体方案介绍···············································32.1数控电压源的方案论证·····································································32.1.1方案一：采用单片机的数控电压源的设计·······································32.1.2方案二：采用调整管的双计数器的数控电压源的设计························32.1.3方案三：采用调整管的十进制计数器的数控电压源的设计··················42.2数控电压源的方案比较·······································································52.2.1数控部分的比较········································································52.2.2输出部分的比较········································································52.2.3显示部分的比较········································································5第3章数控电压源的工作原理····················································63.1整机电路框图···························································································63.2工作原理·······················································································63.2.1DA转换电路工作原理·································································63.2.2电压调整电路工作原理·······························································73.2.3数值计算·················································································8第4章单元电路工作原理··························································94.1时钟电路·······················································································94.1.1时钟振荡电路图········································································94.1.2时钟信号的产生········································································94.2复位电路·······················································································94.3键盘接口电路···············································································104.3.1键盘电路···············································································104.3.2键盘电路工作原理···································································104.4显示接口电路················································································11IV4.4.1显示电路原理··········································································114.4.2LED显示方式··········································································124.4.3显示电路原理图······································································124.5DA转换电路··················································································134.6电源电路·····················································································134.6.1稳压器78L12和79L12······························································134.6.2电源电路原理图······································································144.7所用主要芯片···················································