【正文】 evelopment of the switching power supply. The brief, the situation and trend of development, classification and application, and working principle of high frequency switching power supply are introduced in this paper. It has also told the singleend flyback converter and single slice of switch power chip TOPSwitch Ⅱ instead especially. TOPSwitch Ⅱ series intergrated circuits are produced especially for switching power supply by Power Integration Company ,which integrate PWM and high voltage MOSFET together , and have perfect protection function. Designing low power switching power supply with such integrated circuits can decrease parts count and cost, increase reliability. In this paper the internal construction and principle of TOPSwitchⅡ are introduced, including several typical feedback circuits and a kind of practical electric circuit. A flyback switching power supply based on TOP224Y is presented. Firstly, the principle and characteristics of this Singlechip switching power supply are analyzed. A singlechip switching power supply is designed according to the features of the chip which output power is 22W and output voltage are +5V,12V and +12V. Second, the external circuits of system include five parts, these are input rectifierfilter circuit, high frequency transformer, clampprotect circuit, output rectifierfilter circuit and feedback circuit. According to the design requirements, the detailed analysis of the five parts is presented, calculation of the values of the parameters and selection of the ponents are provided. At last, the power supplies have high efficiency, low ripple, stability output voltage and excellent electrical characteristics, and are used as control power supply of instruments and meters. Keywords： Switching power supply。 Single chip switching power supply。 High frequency transformer 目 錄 1 緒論 .................................................................................................................................1 開關電源概述 .............................................................................................................1 開關電源國內外發(fā)展狀況與趨勢 ..............................................................................2 開關電源的工作原理 .................................................................................................3 開關電源的分類 .........................................................................................................4 開關電源變換器的基本電路 .....................................................................................6 開關電源的應用 .......................................................................................................10 開關電源中的 功率開關器件 ...................................................................................10 課題簡介 ..................................................................................................................11 所選課題的意義 ....................................................................................................11 本課題的研究內容、研究方法 .............................................................................12 2 單片開關電源的工作原理和分類 .................................................................................13 單片開關電源的基本原理 .......................................................................................13 單片開關電源的兩種工作模式 .............................................................................14 單片開關電源反饋電路的四種基本類型 .............................................................15 單片開關電源的產品分類 [9] ....................................................................................16 三端單片開關電源 ................................................................................................16 TinySwitch 系列四端開關電源 ............................................................................19 MC33370 系列五端單片開關電源 ........................................................................20 TOPSwitch 單片開關 電源系列產品 ........................................................................22 TOPSwitch 系列器件簡介 ....................................................................................22 TOPSwitch產品分類、性能及結構特點 ..............................................................23 TOPSwitch Ⅱ系列器件 ........................................................................................25 TOPSwitch II 系列單片開關電源的性能特點 [10] .................................................25 TOPSwitch II 系列單片開關電源的工作原理 .....................................................27 五端單片開關電源的原理與應用 ............................................................................30 TOPSwitchFX 系列芯片的性能特點 ...................................................................30 TOPSwitchFX 的管腳功能和內部結構 ...............................................................30 3 單片開關電源的系統設計 .............................................................................................33 單片開關電源功率計算 ...........................................................................................33 TOP224Y 的主要性能特點和工作原理 ...................................................................33 性能特點 [11] ..........................................................................................................33 工作原理 [12] ..........................................................................................................34 開關電源電路的總體設計 .......................................................................................35 輸入整流濾波電路的設計 ....................................................................................36 高頻變壓器的設計 ................................................................................................37 箝位保護電路的設計 ............................................................................................41 輸出整流濾波電路的設計 [14] ................................................................................41 反饋回路的設計 [15] ............................