Design Of A Circuit-Mode PWM Switching Power Supply Controller

In recent years, with the development of our country's economics as well as the rapid increase of power supply for computers and communications industry, the demand of the switching power supply increases rapidly. Research of switching power supply has become a hotspot in the field of power electronics. Traditional linear regulated power supply is gradually replaced by the core of switching power supply control circuit for its low precision,low efficiency. Therefore, the study of switching power supply controller has great theoretical significance and also has great economic and social benefits.A kind of circuit-mode PWM switching power supply controller chip is designed in this paper based on bipolar technology. At first, the principle of PWM switching power supply controller chip is introduced. Then the principle of Pulse Width Modulation and Pulse Frequency Modulation is analyzed in detail. The trait of voltage feedback mode and the trait of current feedback mode are compared, and current feedback mode is selected to build the converter due to the design specification.According to needed functions, an integrated circuit block diagram is designed along with required parameters. These modules include: high gain PWM comparator circuit,band-gap circuit,oscillator with external capacitance,OVP circuit,OTP circuit and so on. With Cadence EDA, the simulation results of all critical functional blocks are given. The results show that the working temperature range is from 0℃-140℃, the working frequency is 65KHz, the maximum power is 18W. The results of simulation meet the function requirements. The forward design of single-chip switching power supply management IC has been finished.The whole circuit of chip is designed with the CSWC 1.8μm Bipolar process library. The circuits are simulated and verified with Cadence Spectre. The layout is drawn with Cadence Compose and verified through DRC and LVS.