Design Of Green Mode Primary Side Control PWM Control IC XD5173

In this paper, A green PSR (Primary-Side-Regulation) PWM controller IC XD5173is designed. Green mode technology is a linear frequency reduction technology, which can solve the output voltage rising problem and the high power consumption problem at light loads of conventional switching power supply. PSR technology can eliminate optocoupler IC and TL431in conventional SSR (Secondary-Side-Regulation) system, which can reduce the system cost greatly.Firstly, the significance and trends of switching power supply technology are proposed in this paper. Secondly, the basic topologies of switching power supply are described, as well as control methods and modulate modes. Based on the analysis above, the system design, circuit design and simulation of XD5173are given. According the demand of PSR, creative design of a novel voltage sampling circuit for PSR system is proposed. XD5173adopts PWM modulation technology, operates at DCM (Discontinuous Conduction Mode) with CC/CV(Const Current/Const Voltage) regulation function. The operating frequency of XD5173at heavy load is42KHz, which reduces linearly with the lighter load at green mode until the minimum value of550Hz. XD5173only consumpts current of1.8uA at startup stage,3.3mA at normal operating and1.3mA at deep green mode, which saticfies requirement of low power consumption.The design of XD5173is based on0.4um BCD process, and simulated by Hspice. According to the simulation results, the function and performance of XD5173has met the requirements.