基于MC34063芯片DC-DC(20-5)降压型变换电路.doc

目 录基于 MC34063 芯片的 DC-DC(20/5)降压型变换电路 ..................................................................11 引言 ................................................................................................................................................22 设计要求及分析 ............................................................................................................................32.1、设计要求 ...........................................................................................................................32.2、设计分析 ...........................................................................................................................33 MC34063 芯片介绍 ....................................................................................................................43.1、MC34063 的引脚图及引脚介绍 .....................................................................................43.2、MC34063 内部组成及示意图 .........................................................................................43.3、MC4063 芯片 特点 ...........................................................................................................54 系统整体方案的论证与选择 ........................................................................................................54.1、外接开关管方案 ...............................................................................................................54.2、不外接开关管方案 ...........................................................................................................75 基于 MC34063 变换电路的工作原理 .........................................................................................85.1、DC-DC 开关电源的电路组成及工作原理 .....................................................................85.2、基于 MC34063 降压变换电路原理 ..............................................................................106 电路仿真 ......................................................................................................................................196.1、proteus 仿真软件介绍 ....................................................................................................196.2、仿真电路及测试图 .........................................................................................................197 实物测试及结论分析 ..................................................................................................................217.1、实物及测试结果 .............................................................................................................217.2、结果分析 .........................................................................................................................22参考文献 ..........................................................................................................................................23附 录 ................................................................................................................................................24致　 谢 ..............................................................................................................................................27基于 MC34063 芯片的 DC-DC(20/5)降压型变换电路摘 要：本文设计了一种基于稳压开关芯片 MC34063 的 DC-DC 电源变换电路，可将DC/20V 变为 DC/5V，且输出电压准确、稳定，具有低噪声、低功耗性能。

鉴于 MC34063芯片具有周期性占空比可控、可实现直流到直流变换的特点，借助于芯片的开关作用，实现将一定幅值的直流输入电压转变为间断特性的脉动直流输出采用电感、电容组成滤波电路，并在输出端设置由电阻 R1、R 2 组成的取样反馈电路进行实时监测输出端的电压并将信号反馈到开关芯片，进而调节开关的占空比使输出电压准确运用 proteus 仿真软件对整体电路及其关键指标进行了优化模拟，并搭建实物电路，经测试最终电路输出稳定的直流电压 5.07V，无明显波动， 测试精确度约 2%，基本达到设计要求关键字：占空比可控；脉动直流；MC34063 芯片Abstract: Is designed based on the regulator switch chip MC34063 DC-DC power conversion circuits, can be DC/20V into DC/5V, and the output voltage accuracy, stability, low noise, low power consumption performance. In view of the MC34063 chip, can be achieved that the DC to DC transform the characteristics of periodic duty cycle controlled by means of the chip switch role in achieving a certain amplitude of the DC input voltage into a pulsating DC output intermittent characteristics. By inductance, capacitance to form a filter circuit, and set in the output sampling feedback circuit composed of resistors R1 and R2, real-time monitoring of output voltage and the signal fed back to the switch chip, and then adjust the duty cycle of the switch so that the output voltage accurately. The use of the Proteus simulation software optimized analog circuit as a whole and its key indicators, and build a physical circuit, has been tested. The stability of the final circuit output DC voltage of 5.07V, no significant fluctuations, test the accuracy of about 2%, basically meet the design requirements.Keywords: duty cycle controlled; pulsating direct; MC34063 chip1 引言近代关于降压电源基本上有开关电源和线性电源两种，线性电源（Linear power supply）是先将交流电经过 变 压 器 降低电压幅值，再经过整 流 电路整流后，得到脉 冲 直流电，后经滤波得到带有微小 波 纹 电 压 的直流电压。

开关电源就是用通过电路控制开关管进行高速的导通与截止，将直流电转化为高频率的脉冲电流，同时提供给变压器或者整流电路进行变压，从而产生所需要的直流电压，这样的转化往往是高频的转化为高频电流的原因是高频电流在变压电路中的效率要比 50Hz 高很多一般开关电源的控制部分都是在集成片上完成而且工作时不是很热下面就线性电源与开关电源的效率、经济、适用性等方面作简单的介绍线 性 电 源 的 工 作 过 程 是 输 入 电 源 先 经 预 稳 压 电 路 进 行 初 步 交 流 稳 压 后 ，通 过 主 工 作 变 压 器 隔 离 整 流 变 换 成 直 流 电 源 。