Research And Design Of A Half-bridge PWM Controller Integrated With Synchronous Rectification Technology

With the development of electronic technology,there is an increasing demand for industrial electronic products with high integration,high efficiency and multiple functions.Because of its simple structure and lower voltage stress than other isolated topologies,half-bridge converters are widely used in occasions where the input voltage is higher than the withstand voltage of the switch tube.This article focuses on the application of output low voltage and high current scenarios,research and design a PWM controller that integrates synchronous rectification technology and is applied to halfbridge topology.This article first reviews the principles and control methods of PWM control technology.Because of the strong anti-noise ability of the voltage mode and the simpler debugging circuit,the voltage mode is selected.And in order to improve the dynamic response of the voltage mode,the voltage feedforward mode is used for compensation.Then,this article introduces the principle and system design of the half-bridge converter,and analyzes the design of the drive circuit of the half-bridge converter.Finally,this article introduces the basic principles of synchronous rectification and the difference between different driving methods.Based on cost and convenience factors,we choose to integrate the synchronous rectification drive circuit into the PWM chip.The half-bridge gate drive signal and synchronous rectification can be adjusted through external resistors.Timing between driving signals.The PWM chip designed in this paper uses voltage control mode and voltage feedforward mode,the maximum frequency of the oscillator is 2MHz,and the peak current of the half-bridge gate drive port is 8A.In a typical application circuit,the input voltage of the converter is 48 V,the output voltage is 3.3V,and the maximum load current is 30 A.Under the BCD0.35μm process,the results of the verification using the HSPICE simulation tool show that the chip works normally after power-on,the synchronous rectification sequence is normal,the oscillator can reach the maximum frequency of2 MHz,the transient response of the converter is good,and the conversion is under 30 A load.The efficiency is above 90%,and the other parameters of the chip also meet the design requirements.In summary,a half-bridge PWM controller with integrated synchronous rectification technology designed in this article can meet actual application requirements in the front and back simulation results.