The Design Of A Green Energy-saving AC-DC Switching Mode Power Supply Chip

Switching mode power supply(SMPS)because of its small size,light weight,high efficiency and many other advantages,are widely applied in portable terminals,household appliances,computers and other fields,has now become the mainstream power supply products.With the increasingly serious energy crisis,research about low power consumption,high efficiency of switching mode power supply has become an important research topic in the field of power.Therefore,it has great practical significance to achieve green energy-saving AC-DC switching mode power supply.A low stand-by power consumption,high efficiency AC-DC switching mode power supply chip was designed,based on switching mode power supply system for low-power research and design.The chip that uses primary side regulation(PSR)simplify the overall circuit.The volume of system becomes smaller and cost becomes lower.And high-voltage start circuit,quasi-resonant technology,low power supply voltage and mixed modulation mode be adopted to reduce power consumption and improve efficiency.At the same time,the chip has cable compensation and a variety of protection functions.In this paper,the working principle of flyback and forward structure of switching mode power supply,control mode and modulation mode of switching mode power supply are introduced in detail.Then,the working mechanism and characteristics of primary side regulation and secondary side regulation are described.Secondly,the main sources of power consumption in switching power supply system are analyzed emphatically.Based on the factors that limit power consumption and efficiency,several methods of realizing low power consumption and high efficiency of switching power supply are proposed.Including:high-voltage start-up circuit was used to reduce power consumption on the starting resistor,low power supply voltage circuit was designed to reduce the static power consumption of the chip,the quasi-resonant valley position was accurately detected by comparing the feedback voltage amplified by the switching capacitor amplifier circuit with the capacitance voltage and mixed modulation mode was used to reduce switching losses.Then the structure of the chip frame and switching power supply system structure and working principle were put forward.Then,according to the realization method s of low power consumption,high efficiency,the circuit key module is designed.Finally,based on the CSMC 0.5μm CMOS process,the system circuit and the whole circuit of the chip are simulated by Cadence spectre simulation tool.The results of the chip after the tape-out and package shows that the change of the pin voltage and the change of the switching frequency at different loads are in accordance with the simulation results.the chip achieve the well function,the stand-by power consumption of switching power supply system is less than 50mW,efficiency is over 80%.