| In recent years,with the development of semiconductor technology,power management chip has been widely used,in which synchronous rectifier mode PWM DC-DC converter is characterized by its simplicity and efficiency become the most commonly used model in power converter.Based on CSMC 0.25 um BCD technology,this dissertation designs a synchronous rectifier BUCK DC-DC converter,which uses the PWM peak current mode control.Based on the conventional dead time control circuit,this paper presents a simple and fast response adaptive dead time controller,greatly reducing the body diodes conduction time before the synchronous rectifier turns on;Due to the smallest output duty ratio limited,the inductor occurs a small peak current at system start-up under traditional soft start circuit.To solve this problem,a sizing modulation method has been used,by gradually improving the size of main switch to control the inductive voltage at system start-up,the peak current of the inductor at the beginning of the system startup is greatly suppressed.This paper introduces the rule of parameters design of BUCK DC-DC converter,and completes the design and layout of the important modules,the simulation results satisfy the design requirements.The converter input voltage range from 9V to 15 V,the output voltage is 5V,the maximum load current is 1A,the converter operates at the frequency of 1MHz,and the highest efficiency of converter is up to 91%. |
PDF Full Text Request