Design Of Primary Side Feedback PWM Control AC/DC Converter XD1432 With Constant Current And Constant Voltage Output

In this society, electronic devices get close to people’s daily life and work.And power management chip is very important because of their small size, light weight, high reliability and wide range of output voltage. With electronic devices getting close to people’s daily life and work,power efficiency, low power consumption, small size and other characteristics of power supply have become more and more important. In order to meet the above requirements, a primary side feedback flyback PWM control output constant current and voltage AC-DC converter chip XD1432 is designed in this paper, based on the science project “Design and research of CC / CV AC-DC power converters” of Key Lab of High Speed Circuit Design and EMC Ministry of Education in Xi’dian University.Firstly, a analysis of the switching power supply history,development background and current situation at home and abroad is given. A detailed analysis of the switching power supply classification, the working principle,control and feedback for the design of management chips is given on this basis, which provides adequate theoretical basis for IC design. A detailed analysis of the switching power supply control and feedback for the design of management chips is given on this basis, which provides adequate theoretical basis for IC design.Secondly the detailed system-level design solutions of chip XD1432 is proposed,according to the chip design performance requirements. At last, the key sub-module circuit design and simulation is completed.The chip uses a primary side feedback technology, and eliminates the optocoupler and TL431 and other components,which reducing the chip area and saving cost. The chip designs control circuit and protection circuit, such as undervoltage lockout(UVLO), internal power generating circuit, with second-order temperature compensated bandgap reference(VREF), oscillator(OSC),leading edge blanking(LEB), error amplifier(EA),soft drive, cable compensation and over-voltage protection circuit,over-temperature protection(OTP) cycle-by-cycle current limit protection(OCP), overvoltage protection(OVP), undervoltage lockout(UVLO), and so on. The chip has a high-precision CC/CV characteristics, the chip adopts PFM in CC mode and adopts PWM in CV mode. The chip has a soft start module functions to prevent the circuit damage due to starting inrush current and the soft start time is 17 ms.Comprehensive protection functions, frequency jittering circuit is intergrated in oscillator circuuit which changes frequency of oscillator and eliminates noise and improves EMI performance greatly. So the area reduces and the design simplifies. The chip also sets a clamp circuit which keeps the gate drive output lower than 16 V for the purpose of effective protection of the built-in high-voltage power MOSFET switch. The chip also uses a programmable output cable drop compensation, improveing load regulation greatly.A primary PSR flyback PWM control constant current output AC-DC converter chip XD1432 is based on 1μm 40 V BCD process. It works in DCM(Discontinous Conduction Mode) and uses Cadence Spectre to simulate every module and verifies the overall performance. Through simulating circuit,the measurement shows that the CC point is 1A. The tested results show that the chip has a good constant current and voltage capability, and performance indicators and circuit functions meet the design requirements.