Design Of Constant Current/Constant Voltage AC/DC Converter XD3037Based On Primary Side Feedback

The scientific research and practical applications have been combined to design aAC/DC converter XD3037based on the principles of AC/DC Switching Mode PowerSupply (SMPS). The chip XD3037is controlled by the primary side feedback signal,which is a novel way of feedback control.First of all, The basic working principle and control model of the AC/DC converterare introduced detail in this paper, which makes full theoretical preparation for thedesign of the chip XD3037. Next, according to the application environment, thefunction and characteristic indexes of the chip XD3037is made. Finally, a detailedsystem design program is proposed in accordance with the design requirements, and acircuit is achieved based on the design program. The use of the current PWM feedbackcontrol method, the Constant Current/Constant Voltage (CC/CV) output mode ofoperation, greatly enhanced the system’s the transient response performance andconversion efficiency. A green mode control circuit is designed to check voltage at loadfeedback pork, which controls the switching frequency through detecting the loadvoltage feedback, and which makes the system automatically go into green mode underlight load condition, thus reducing light load consumption, and realizing highconversion efficiency over a wide load range. The frequency jitter function of oscillatorwhich can spread the spectrum of clock signal is used to reduce effects of EMI. Thefunctions and working principle of main modules in XD3037is introduced andanalyzed in details.The design and simulation of the chip XD3037are completed by Cadence andHspice software based on0.5μm BCD process. The results show that the chip XD3037has good performance of CC/CV output, its function and characteristic indexes bothmeet the design requirements.