Design of multifunctional flyback switching power supply

With the peak current PWM control IC UC3842 as its core,a multifunctional flyback switching power supply is designed,which has 6 channels of isolated DC voltage output.Its operating principle and peripheral circuit are introduced.The EMI suppression circuit is designed to meet the requirements of electromagnetic compatibility and safety.The design of a new-type snubber circuit for transformer windings is introduced in detail and the design of its transformer is emphasized,including the calculation of Zener clamping voltage,actual duty-cycle ratio and inductance,the selection of magnetic core,and the determination of winding turns and air-gap.The negative feedback regulation of output voltage and various protective mechanisms are realized.Experimental results show that the designed switching power supply has stable voltage output,small ripple,high voltage and load regulation rates,small size,light weight and excellent electromagnetic compatibility.