节点文献
开关电源-DC/DC转换器的设计
【作者】 朱志勇；
【作者基本信息】 电子科技大学 ， 电子与通信工程， 2009， 硕士
【摘要】 现在国内便携式产品的迅猛发展带动了DC/DC开关电源的飞速成长,体积更小、功耗更低、效率更高的产品不断涌现。本文将先从DC/DC开关电源的分类、原理、典型结构等方面进行说明,然后专门针对PWM工作模式详细阐述,最后配合项目(一款小型、高效、PWM降压型DC/DC转换器)做进一步的分析,对其所用电路的考虑、值的确定,通过计算、仿真进行推敲,以完成此论文。本论文第一章介绍了课题研发背景和DC/DC开关电源的国内外发展现状;第二章介绍了DC/DC开关电源的分类和各自的工作原理;第三章详细介绍了应用广泛的PWM调制工作模式,同时,这种工作模式也是这次课题研发项目采用的主要工作模式之一;从第四章开始,着重介绍项目详细情况;第五章重点介绍项目仿真分析结果;第六章是版图和工艺上的一些考虑;由于项目中采用大量电阻电容和修调,第七章补充说明了常见的电阻电容和修调方法;第八章介绍了项目的投片测试情况;第九章总结。本文重点在于DC/DC开关电源的设计,本课题项目是一个低噪声、脉宽调制(PWM)、DC/DC降压转换器。它在手机、PDA通讯和便携式终端等小型无线系统中用作逻辑电源和传输工作。该器件的特点是在内部集成有同步整流管,因而可以在不需要额外肖特基二极管的情况下取得较高的效率。本项目出色的噪声特性和固定频率工作能很容易实现快速滤波,非常适和应用于Li-Ion电池或其他+3V或+5V固定输入中。转换器可以工作在以下四种模式之一:强迫PWM模式工作在与负载无关的固定频率中;同步PWM模式允许外接一个开关转换频率,这样能控制噪声并能使噪声降低到最小;在轻负载期间通过开关转换成PFM冲激模式,这种理想模式(PWM/PFM转换)延长了电池的寿命;关闭模式把静态供电电流降低到0.1μA以下,使该器件处于待机状态。
【Abstract】 The fast development of handy-terminals drives the growth of DC/DC converters. Small, low power, high efficiency produces are more and more popular. At first, this thesis will introduce the DC/DC converter’s classify, elements and typical structure. And then, based on a program (a small, high efficiency PWM DC/DC converter) make farther analysis.The first chapter of this thesis is an introduction of DC/DC converter. Chapter two class the DC/DC and explain the elements. Chapter three shows the details of PWM mode—the most popular mode. Chapter four comes to the project of a small, high efficiency PWM DC/DC converter. Chapter five is the simulation of the project. Chapter six is the layout of the project. Chapter seven refers to the integrate resistors and capacitors. Chapter eight is the summarize.The emphasis of this thesis is the design of a DC/DC converter. This converter is a low-noise, pulse-width-modulated (PWM), DC-DC step-down converter. It powers logic and transmitters in small wireless systems such as cell phones, communicating PDAs, and handy-terminals. The device features an internal synchronous rectifier for high efficiency; it requires no external Schottky diode. Excellent noise characteristics and fixed-frequency operation provide easy post-filtering. It is ideally suited for +3V or +5V fixed input applications.The device operates in one of four modes. Forced PWM mode operates at a fixed frequency regardless of the load. Synchronizable PWM mode allows an external switching frequency to control and minimize harmonics. Idle Mode (PWM/PFM) extends battery life by switching to a PFM mode during light loads. Shutdown mode places the device in standby, reducing quiescent supply current to under 0.1μA.