【文章內容簡介】 laid a good foundation. In the late 9039。s, along with the development of integrated circuit, the monolithic integrated circuit switching power supply of various types of. It will switch power suppl y of pulse width controller, power output stage, protection circuit in a single chip, isolated switching power supply can form high efficiency without transformer. The representative of Holland Philips pany in 2021 to develop the TEA1520 series switching power supply, American Onsemi pany 1998~2021 has developed NCP1050, NCP1000 series single chip switching power supply, USA Motorola pany in 1999 launched the MC33370 series of five terminal switch power supply, America PI pany in 1994 launched the first TOPSwitch series is the first generation product, was hailed as a top switch power, the 1997 launch of the TOPSwitch II series, launched in 1998 2021 launched TinySwitch series, TOPSwitchFX series, then introduced the TOPSwitchGX series, and promoted as a mainstream product. Based on the TOPSwitchGX series TOP247Y for example to explain its characteristics and typical design application. Two: TOPSwitchGX series of six terminal switch power supply chip characteristics Design of a single end flyback offline switching power supply, involving many aspects of Electrical Engineering: structural simulation circuit and digital circuit, characteristics of bipolar transistor and MOS power tube device, magic materials, heat temperature, overcurrent and overvoltage protection control circuit, stable performance etc.. This presents a great challenge: its design involves many variables to the prehensive coordination. It is due to the highly integrated TOPSwitch, which makes the design task is greatly simplified. Because it effectively reduces the design variables and the establishment of the project, the stability of IC internal loop, so bee a step by step design method is simple, making it easy to follow the reference, and guide readers from the design flow chart of TOPSwitch, fast to get satisfactory result. In the process of optimal data and information, can be used as basic data of the key design guidelines, such as some equations and guide icons. Between the three above, they provide before and after the mutual reference content, so the reader can broaden thinking, the implementation of the relevant procedures in a given period, to achieve the best parameters, it is helpful to understand and optimize the data. Due to the highly integrated TOPSwitch device circuits, some debates of the past design of this kind of power supply, can be solved in the chip. Only a small amount of need adjustment device in IC outside to arrange, which can maintain the basic circuit structure of the invariant. Feedback on the special converter application requirements, such as constant current output, constant power output, see the relevant documents. The feedback circuit with TOPSwitch, only need to add some improvement measures in the converter circuit basic structure, because they are all arranged on the periphery of the IC. There are four different feedback forms are available, including two kinds of feedback loop is controlled by optocoupler. Two other kinds of feedback loop is bias winding only connecting RC (or on) to IC. Depending on the power switch on the output of voltage and current requirements. 1 internal TOPSwitchGX mainly consists of a control voltage source, bandgap voltage reference, oscillator frequency jitter, pulse width modulator, shunt regulator / error parator, gate drive and output, high voltage power switch (MOSFET), bias circuit, overcurrent protection circuit, an overvoltage, undervoltage detection and protection circuit, overheat protection circuit, a power on reset circuit, soft start circuit, light load automatically reduce the switching frequency circuit, logic, threshold voltage 1V voltage parat