Stability Analysis And Design Of BUCK DC/DC Controller With Current Mode Control

With the rapid development of society,electronic devices like mobile phones,tablets,laptops have become an indispensable part of our daily life,and all these devices can't work without power supply,so the power management IC is particularly important.The switching power supply with many advantages like high conversion efficiency,small size is widely used.In order to ensure switching power supply can work steadily,the analysis of the loop stability is an essential step in the design process of switching power supply.This thesis has designed a peak current mode Buck DC/DC controller with input votage range of 4~36V,output votage range 0.8~10V and very low quiescent current.This controller can work not only in fixed frequency mode(200kHz?400kHz?600kHz),but also in the mode which followed the external clock.Background and significances related with the subject and some knowledge about switching power supply,including the development status and trend of switching power supply are firstly introduced.Then,in order to analyze the loop stability of switching power supply,the basic idea and some common methods of building small signal model including state space average method and switch network average method are researched.Then small signal model of peak current mode buck dc/dc converter based on Ridley's model is presented.After that,this thesis designs the framework of controller,gives a brief introduction about the working principle of system,and studies the selection method of peripheral devices.Then based on the small signal model,the value of slope compensation and the compensation network are designed to ensure the loop stability.And this thesis also designs and simulates some important modules like reference module,error amplifier module,oscillator module,slope compensation module,drive module,and the analysis of these modules are also be presented.This thesis simulates the loop stability using MATLAB,and simulates the whole system using HSPIC based on HHNEC 0.35?m BCD process.The simulation results show that the chip designed in this thesis meets the stability requirement and performs well.The parameters like line regulation,load regulation and conversion efficiency meet the design requirements.