Switching Power Supply Technology

With the development of power electronics, switching mode power supply (SMPS) must have higher frequency, higher power density, higher efficiency, higher power factor (PF) and higher reliability. To be practicability,the circuit must be simple and small. And to achieve these, people have done much work in power devices selection, topology research, control circuit, and power devices layout. However, depended on the designer's experience, the design maybe a better one, but always not the best.Motivated by emerging portable applications that demand low-power Hardware to maximize battery life-time, and reduce the requirement of package, high-efficiency DC-DC conversion is better selection.The thesis is a conclusion of a high efficient DC-DC converter design. Particularly discussed the pulse width modulation (PWM) control and the pulse frequency modulation (PFM) control of a buck DC-DC conversion. Analysis the advantages and disadvantages between the both control technologies, and provide a solution.The DC- DC conversion of the thesis adopted a PFM/PWM control technology which excelled to both PWM and PFM, the DC-DC converter can make the efficiency much than85% from current load 1mA to 600mA when the regulator out put voltage is 12V.It is a particular description about the design of the system structure and the crucial functional blocks.In this thesis, the proposed current mode buck converter senses the inductor current variation to accelerate response time, and applies the mechanism of feedback-loop theory to control the output voltage at the desired value. Compared with the voltage mode buck converter, the current mode buck converter has better load regulation, better line regulation and faster transient response. The proposed buck converter has high efficiency, and therefore, it is suitable for the application of portable products.Simulate all critical functional blocks and give results with Spectre. Select different components, simulate the system and give the results about system characters. The result showed the efficiency at the variable loads.