PWM电流模式DC-DC降压控制电路的设计

PWM电流模式DC-DC降压控制电路的设计当今消费市场中，便携式电子产品所占比重较大，这种产品要求电池体积小、重量轻、使用时间长。高效、低压开关DC-DC转换器，通过提高电源转换效率及改进控制技术，达到了所需要求，因此被广泛应用于电子产品中。本文首先介绍了BuckDC-DC转换器的拓扑结构及工作原理，并且详细论述了两种工作模式。然后进行了系统的设计与分析，具体介绍了电流感应电路、过流保护电路、带斜坡补偿的振荡器以及同步整流驱动电路等系统关键模块的设计与仿真。其中，振荡器电路的设计中，利用一种简单的斜坡补偿电路，完成了窗口比较式振荡器的充放电电路的功能，具有简洁高效的特性。同时，在模块电路设计中，采用0.35µm工艺，从功率级设计开始，详细讨论了元件类型的选择以及电路结构参数的确定。之后，配以简单的外围电路构成了BuckDC-DC转换器系统，并对其进行了功能仿真，Hspice仿真结果表明，该系统能稳定工作，并满足设计指标的要求。关键词：PWM峰值电流模式；BuckDC-DC转换器；带斜坡补偿的振荡器Title：DESIGNOFCURRENT-MODEBUCKDC-DCCONVERTERCONTROLICMajor：MicroelectronicsandSolidElectronicsName:李强Signature:Supervisor:AssociateProf.LuGangSignature:AbstractIntoday’sconsumermarket,battery-operatedportableelectronicdevicesareingreatdemand.Forthesedevices,smallsize,lightweight,andlongbatteryrun-timearethemaindemands.Thehighlyefficientlow-voltageswitch-modeDC–DCconvertersaremandatoryinthesedevicesforminimizingthesizeandweightandextendingthebatteryrun-time,byenhancingtheefficiencyofpowersupplyandimprovingthecontroltechnology.ThetopologystructureandbasicprincipleofbuckDC-DCconvertersareintroducedfirstly.Meanwhile,twooperationmodesaredepictedindetail.Thenthewholesystemisdesignedandanalysis.Andthekeymodules,suchascurrentsensingcircuit,overcurrentprotectioncircuit,andsynchronousrectifyingdriver,aredesignedandmodulated.Asimpleslopecompensationcircuitisusedtosubstituteforcharginganddischargingcapacitorinthewindowcomparatoroscillator.Andtheoscillatorissimpleandeffective.Inthemoduledesignpart,startingwiththepowerstage,thetypeandparametersselectionofelectronicdevicesarediscussed.Finally,awholeBuckDC-DCconvertersystem,whichcanbecompletedbythecontrolICwithfewexternalparts,issimulatedbyHspice,with0.35µmCMOSprocess,whoseresultsindicatethatthesystemisstableandcircuitfunctionandperformancehaveperfectlysatisfiedthedesignrequirements.Keywords:PWMpeakcurrent-modecontrolmethod;BuckDC-DCconverter;oscillatorwithslopecompensationcircuit1引言11.1开关电源的发展..........................................................................................................11.1.1开关电源的发展现状......................................................................................11.1.2开关电源的发展趋势......................................................................................21.2开关电源的分类与比较..............................................................................................31.3本文的主要工作..........................................................................................................42DC-DC转换器的拓扑结构和原理分析52.1BuckDC-DC转换器的工作原理分析.........................................................................52.1.1CCM模式分析.................................................................................................62.1.2DCM模式分析.................................................................................................92.2DC-DC转换器的控制方式和控制模式....................................................................112.2.1DC-DC转换器的控制方式............................................................................112.2.2DC-DC转换器的控制模式............................................................................123PWM电流模式DC-DC降压控制电路的设计与分析173.1系统设计目标及系统结构........................................................................................173.2误差放大器的设计与仿真........................................................................................183.2.1电路的分析与设计........................................................................................183.2.2电路的仿真结果............................................................................................223.3带隙基准电压源的设计与仿真................................................................................243.3.1电路的分析与设计........................................................................................243.3.2电路的仿真结果............................................................................................273.4PWM比较器的设计与仿真.......................................................................................303.4.1电路设计与分析............................................................................................303.4.2电路仿真结果................................................................................................313.5电流感应电路与过流保护电路的设计与仿真........................................................333.5.1电流感应电路设计与分析............................................................................333.5.2过流保护电路的设计与分析........................................................................353.5.3电路的仿真结果............................................................................................363.6带斜坡补偿的振荡器电路的设计与仿真................................................................383.6.1比较器的设计与分析....................................................................................393.6.2斜坡补偿电路的设计与分析........................................................................404.6.3脉冲展宽电路的设计与分析........................................................................423.6.4仿真结果........................................................................................................433.7逻辑控制电路与同步整流驱动