中北大学2013届本科毕业设计说明书设计要求；设计一可调恒流源电路，输出电流范围2mA～20mA,最小刻度0.5mA,波动小于0.1mA可调恒流源设计摘要本系统以直流电流源为核心，MC34063为主控制器，通过电位器来设置直流电源的输出电流，并可由数码管显示实际输出电流值和电流设定值。本系统由单片机程控输出数字信号，经过D/A转换器（AD0804）输出模拟量，再经过运算放大器隔离放大，控制输出功率管的基极，随着功率管基极电压的变化而输出不同的电流。单片机系统还兼顾对恒流源进行实时监控，输出电流经过电流/电压转变后，通过A/D转换芯片，实时把模拟量转化为数据量，再经单片机分析处理，通过数据形式的反馈环节，使电流更加稳定，这样构成稳定的压控电流源。关键字:MC34063，恒流源，单片机，A/DAdjustableconstantcurrentsourcedesignAbstract第1页共41页中北大学2013届本科毕业设计说明书InthissystemtheDCsourceiscenterandMC34063ismaincontroller,outputcurrentofDCpowercanbesetbyapotentiometerwhichsteplevelreaches1mA,whiletherealoutputcurrentandthesetvaluecanbedisplayedbyLED.Inthesystem,thedigitallyprogrammablesignalfromSCMisconvertedtoanalogvaluebyDAC(AD0804),thentheanalogvaluewhichisisolatedandamplifiedbyoperationalamplifiers,issenttothebaseelectrodeofpowertransistor,soanadjustableoutputcurrentcanbeavailablewiththebaseelectrodevoltageofpowertransistor.Ontheotherhand,Theconstantcurrentsourcecanbemonitoredbythesystemreal-timely,itsworkprocessisthatoutputcurrentisconvertedvoltage,thenitsanalogvalueisconvertedtodigitalvaluebyADC,finallythedigitalvalueasafeedbackloopisprocessedbysothatoutputcurrentismorestable,soastablevoltage-controlledconstantcurrentpowerisdesigned..Keywards:MC34063,constantcurrentsource,singlechipmicrocomputer,A/D第2页共41页中北大学2013届本科毕业设计说明书目录1引言......................................................................................................................................21.1研究目的和意义.........................................................................................................21.2国内外发展状况.........................................................................................................21.2.1国外发展现状..................................................................................................31.2.2国内发展现状..................................................................................................31.3本文欲采取的研究方法............................................................................................42设计方案..............................................................................................................................52.1总体方案....................................................................................................................52.2MC34063恒流源系统.................................................................................................62.3电流显示系统............................................................................................................72.3.1单片机STC10F08XE........................................................................................82.3.2单片机晶振部分.......................................................................................................92.3.3单片机复位部分...........................................................................................102.3.4数码管显示部分..............................................................................................
