Research And Design Of Buck DCDC Converter Based On Current Mode

Due to the rapid development of semiconductor technology,electronic products entry the public’s vision and improve people’s quality of life.As an important part of various electronic products,power management chips have more and more application fields,and the market scale is also growing.Switch mode power supplies are widely used in power management chips due to their high efficiency and small size.This paper introduces the current situation and development trend of switch mode power supplies,analyzes the topology and working principle of DCDC converter,and designs a Buck DCDC converter based on current mode.In this paper,the synchronous rectification is adopted to reduce the power loss on the diode in the freewheeling stage.PWM mode is adopted and the internal clock frequency is set to 1 MHz to reduce the switching loss.The converter can achieve fast transient response because of its peak current mode,and a fixed-slope slope compensation circuit is used to suppress the subharmonic oscillation phenomenon.Moreover,the perfect control and protection modules such as on-chip soft start circuit,zero crossing detection circuit,over temperature protection circuit and dead time control circuit are designed to ensure that the converter can work properly.In this paper,the circuit design is based on 40 nm process,the system layout is drawn,and the circuit is simulated and verified.The simulation results show that the converter can obtain a stable output voltage of 1.8 V in the input voltage range of 3 V～3.6 V,the output voltage ripple is less than10 m V,and the efficiency can reach more than 90% when the current is loaded with 300 m A.The transient response of the device is stable when the load current jumps between 30 m A and 300 m A.