Design Of A Current Mode PWM Switching Power Supply Controller

From 1947 the world's first point of contact with the invention of the transistor to 1957,the United States the first orbiting satellite "probe" using transistors,and now to the computer chip,the semiconductor industry has created a great miracle.The 21 st century is destined to be a fantastic century,in this incredible era,China's countless hot exploration of scientists are constantly creating a miracle of science and technology,from the manned spacecraft to the dragon submersible,Tablet PC,LCD,MP3 Players,Walkman,digital cameras,etc.,many previously unimaginable things have become a reality.In this context,the semiconductor components are widely used in a variety of electronic products,to promote China's economic take-off can not be ignored a force,in turn,the development of the national economy has further promoted the application of electronic equipment.Electronic equipment for high-speed response,high efficiency,high power density,low power consumption and other needs,but also continue to promote the power management chip market development and growth.Power supply as the electronic engine "engine",for the normal work of the circuit to provide energy.The switching power supply with its small size,easy to carry,energy saving and other characteristics,has been widely used in consumer electronics products,an important way to become the field of power.Especially in recent years,portable equipment market demand is huge,as China's new economic growth point,which provides a broad market for switching power supply.In order to meet a wide range of new electronic equipment,the development of the national economy into new vitality,switching power supply control chip has become the focus of research.In This thesis,we design a current mode PWM switching power supply controller.The control chip has the advantages of low starting current,low power consumption,high operating frequency and fast response speed.Three common structures of switching power supply are introduced first.Then,the working mode and modulation mode of switching power supply are introduced by Buck switching power supply,and the advantages and disadvantages of current mode and voltage mode are compared and analyzed.Then,the principle of slope compensation is introduced,and then the conversion efficiency of switching power supply is analyzed.Finally,according to the principle and characteristics of current mode PWM switching power supply,we propose a current mode PWM switching power supply controller,and also introduce its basic working principle.Finally,the design of the overall circuit is completed based on 0.35?m BCD process,including pre-bias power supply voltage circuit,high-precision power supply voltage circuit,pre-bias current circuit,high precision bias current circuit,undervoltage protection circuit and overcurrent protection circuit.According to the design requirements of each sub-circuit,we detailed analy hwo to achieve their functions,and the overall simulation of the system to verify the key performance indicators.The The working principle of each sub-circuit is analyzed and verified in detail,and the whole simulation of the system is carried out to verify the key performance indicators.The simulation results show that the chip meets the design requirements and has practicality.