Research On Key Technologies Of Synchronous Rectified Buck DC-DC Converter

The rapid development of semiconductor technology has led to the introduction of all kinds of electronic and electrical technologies into the market,there is a shortage of energy management chips,and their performance indicators directly influence the quality of electronic products.DC-DC converter chip is the foundation and core of all switching power supplies,its development trend is higher frequency,smaller and more efficient,conducive to saving energy consumption.The high frequency of DC-DC converter can effectively reduce the volume of inductor capacitance of peripheral passive devices,in line with the development needs of electronic equipment portable and compact,so improving the key technical indicators of DC-DC converter under high-frequency conditions is the improvement direction of current research and design.The objective of this thesis is to investigate the key technology of Buck DC-DC synchronous rectification converter,and the circuit adopts the control mode of voltage mode PWM modulation,and the circuit efficiency is improved by synchronous rectification technology.In this thesis,the basic principle of switching power supply is first discussed and then the framework structure and design indicators of DC-DC converter are advanced,and performs a detailed design principle analysis of its key submodules,and ensures the normal operation of the circuit through simulation verification,including the integrated LDO module,error amplifier module,comparator module,oscillator module,bootstrap and dead time control module and overtemperature and overvoltage protection circuit.From the perspective of stability,reliability and safety of the DC-DC converter system,this thesis innovatively proposes an overvoltage protection circuit based on a transistor,which is self-biased and does not require an external reference voltage,and the circuit structure is simple.This thesis is based on the basic switching power supply theory and uses the type compensation method to design the device parameters for the DC-DC converter,and simultaneously performs system level simulation verification of key DC-DC converter indicators at high switching frequencies,testing its wide voltage range,obtaining the ripple voltage under different conditions and then simulating the regulation and efficiency of the load.All circuits in this thesis are verified in the Spectre environment of Cadence software,and all circuit designs are based on the 0.18 BCD process,as well as a DC-DC converter with an 8V to 24 V input voltage range,an output voltage of 5V,a maximum output current of 2A,and an operating frequency of 1MHz is successfully completed.Through system-level simulation,it is verified that under the condition of input voltage of 8V and output current of 1A,its peak efficiency can reach 91.07%,and the voltage ripple rate is 0.0248%.