Design Of A Peak Current Mode Controlled PWM Fly-back AC/DC Converter

Nowadays,the electronics industry is in rapid development,so electronic devices need excellent power supply products.Compared with linear power supplies,switching power supply has the advantages of small volume,high efficiency,high reliability,so most widely used.In this paper,a Fly-back AC/DC converter with pulse width modulation and peak current mode control is designed.Firstly,the overall circuit structure of the chip is designed and the principle of the chip is introduced.Then,the functions and circuit designs of the internal sub-modules in this chip are analyzed in detail.This chip can detect the load condition according to the feedback of the output,so as to adjust the switching frequency of the power MOSFET to improve the conversion efficiency.The main control circuits of the chip include a reference voltage module,a bias current module,an oscillator module,a pulse width modulation module,etc.Inside the chip,there are modules such as under-voltage latching,cycle-by-cycle current detection,and over-temperature protection to ensure the safety.AC input voltage of this chip is 85V-265 V,output voltage is 12 V,the maximum output power that can be provided is 60 W.Based on CSMC 1?m CMOS process,the circuit is simulated,the layout is designed and verificated.Finally,the test result shows that the chip meets the expected specifications and works excellently.