Reserch Of BUCK DC-DC Converter With Wide Input And High Efficiency

With the development of semiconductor technology and chip design capabilities,power management chips with high efficiency,low cost,more stability and can be applied to more occasions have received national attention,but the design capability of power management chips in China is relatively weak.As an indispensable chips in the DC converter chip,the step-down DC-DC converters with the wide input voltage and high-efficiency have very important practical significance.Therefore,a kind of wide input voltage and high efficiency BUCK DC-DC converter was designed in this paper.The application range of traditional BUCK DC-DC converter is limited due to its fixed input voltage and narrow input voltage range.For this kind of problem,combining the wide input frame of high voltage resistant linear regulator and current sense frame with high voltage and high precision,an integrated high-voltage wide input linear regulator and a high-voltage-resistant current sampling circuit module were proposed,which enables the converter to operate over a large input voltage range,and the input voltage range from 5 V to 35 V.Aiming at the low voltage accuracy and slow response speed of traditional structures,a system feedback loop combining pulse width modulation(PWM)and current mode control is proposed.At the same time,the synchronous rectifier technology is adopted to improve the efficiency of the converter,and the power supply selection logic of the integrated linear voltage stabilizer is designed to further reduce the power loss of the internal linear voltage stabilizer,which improves the converter efficiency effectively.An oscillator module that regulates the operating frequency of the system and synchronizes with the external input clock frequency is integrated internally,allowing the converter operating frequency to be flexibly selected based on the application.Aiming at the problems of overcurrent and overvoltage of the vulnerable circuit structure,a simple and efficient design of corresponding protection modules such as output overcurrent protection and zero-crossing protection is proposed.Based on the 0.18 μm BCD process of SMIC,the converter uses Cadence to complete the circuit design,circuit simulation and circuit optimization of key modules to meet the requirements of system design.The simulation results show that the conversion efficiency can reach over 90%.When the load current is around 2 A,the conversion efficiency is about 93%.The input voltage range is 5-35 V,the output voltage ripple is less than 19 mV,the linear regulation rate of input voltage is 0.012%,the load regulation rate is 0.0068%,and the working frequency of the converter is 100 KHz-1000 KHz,which can meet the design requirements of wide input voltage range and high efficiency.