Research And Design On Primary-side Regulation Flyback Converter With Wide Range And High Power Density

As mobile electronic devices such as M/T and lap-top have entered thousands of households these years,as an indispensable module in various electronic products.PM chips face more chances.The primary-side feedback flyback converter has a wide range of application scenarios due to its advantages of low consumption,miniaturization,high power,and wide input range.Aiming at the development trend of the primary-side regulation flyback converter,this paper proposes a wide-range,high-power-density flyback converter.This design directly samples from the primary side without requiring other components to achieve the miniaturization of the chip and achieve high The effect of power density.Through the comparison of CCM,DCM,and BCM,the chip designed in this paper works in BCM under heavy load and DCM under light load to comply with Consider the compromise between chip power consumption,size,and efficiency.According to the basic structure of the primary-side feedback flyback converter,this paper designs a low-dropout linear regulator module for internal circuit power supply.It is verified under different process corners,different temperatures,and different loads,and the output voltage error is 8%as the maximum value for input voltage range from 3?32V.A soft start circuit for system startup is designed,the response time is 13?48.Ins when the system is powered on,and the response time is 55?97.9ns when the system is powered off.A Darlington BJT and MOS are designed in the composite drive circuit can quickly pull the grid voltage of the power transistor.The simulation results show that under different situation,the power transistor's turn-on response time is 6.63?37.89ns,and the turn-off response time is 9.44?47.89 ns,with different VIN.The design of the "knee point"detecting circuit is emphasized,and the circuit is simulated and verified under different situation.When the off time is 400ns,the maximum system sampling error is only 2.55%.At the same time,this article introduces the specific working mode of the chip in a process,and theoretically derives and calculates the peripheral parameters of the chip such as inductance,sampling resistance,feedback resistance,transformer turns ratio,RC snubber circuit,etc.Finally,the chip designed in this article was simulated under the process supporting diode,CMOS,and DMOS with a line width of 0.35?m.The simulation results show that output accuracy is 98.75%,output power is 1.42W,and power density is 2.85mW/mm3 under heacy load,which met the design requirements.The chip proposed in this article has completed the layout design and taped out.