Overview:
This paper introduces the basic principle of the switching power supply, and the structure of the Topswitch II type switching chip. It discusses the selection of the switching tube and the calculation of the main component parameters based on the design process of the small power universal switching power supply. Finally, through the simulation test, the design process of the power supply was certified.
0 Introduction DC regulated power supply is an important part of modern power electronic systems. A good DC power supply system is an important guarantee for high quality modern electronic systems. Switching power supplies have a wide variety of design methods and complex and diverse methods. Therefore, it is necessary to study a simple method to quickly design the general-purpose high-efficiency, low-cost switching power supply.
1 Switching Power Supply Working Principle Switching DC regulated power supply is formed based on the average value of the square wave voltage and its duty ratio and the integral characteristics of the inductor and capacitor circuits. The basic working principle is that the input AC voltage is first rectified to form a pulsating DC voltage, which is transformed by a DC-DC conversion circuit, and then a high-frequency alternating current of different pulse width is formed by the chopper circuit, and then the rectification and filtering output thereof is required. Voltage and current waveforms. If the output voltage waveform deviates from the required value, a current or voltage sampling circuit performs sampling feedback. After comparing the voltage value with the comparison circuit, the difference signal is amplified to control the pulse frequency f and the duty ratio D of the switching circuit. In order to control the conduction state of the output. Therefore, the output voltage and current can be obtained at the output.
As shown in Figure 1, the switching power supply module is divided into the following sections.
According to the actual needs of the power system, by analyzing each part, the corresponding switching power supply products can be designed. 
Figure 1 is a block diagram of the switching power supply.
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SMD transformer Description: small size, high working frequency, high adhesion performance, small distribution inductance;It is mainly used for module power supply, laptop, mobile phone and ultra-thin electric appliance.
The transformer consists of an iron core (or magnetic core) and a coil. The coil has two or more windings, of which the winding connected to the power supply is called the primary winding and the rest is called the secondary winding.It can change ac voltage, current and impedance.The simplest core transformer consists of an iron core made of a soft magnetic material and two coils with different turns on the core.
SMD Transformer, Ee16 Transformer, Power Transformer, Electric Transformer
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