Design Of A Constant Voltage And Constant Current AC/DC Converter Based On The PSR

Based on the project of "research on flyback constant current and constant voltage(CC/CV) AC/DC converters" taken by the Institute of Electronic CAD in XidianUniversity, a CC/CV AC/DC converter chip Based on the technology of PSR (PrimarySide Regulation) was proposed in this paper. Mainly used in small power adapter, phonecharger and LED drivers, the chip operates in discontinuous conduction mode (DCM)and uses the mode of constant voltage and constant current.With the disadvantages of high cost and low reliability, the secondary feedbacktechnology is adopted in traditional AC/DC converter chip. To save the area of layout,reduce manufacturing costs, and effectively improve the reliability of the system, thechip uses a new type technology which called primary side regulation (PSR) technologyin this paper. It has a very broad application prospects on the market which requires achip with low cost and small size. At the same time, for solving the problem of the dropdue to the cable loss which brought by the primary side regulation technology, the chipdesign a cable compensation circuit to compensate the drop voltage of the cable linebrought by different loads under CV mode. The chip ultimately maintains the level ofthe CV curve and achieves a very high precision of constant current/constant voltagecharacteristic. In addition, in order to prevent the chip from shutdown by malfunctionswhich caused by the over-temperature protection circuit, the over-temperatureprotection circuit contains a delay circuit in this chip.The chip uses a0.5μm BCD process, and completes the simulation and functionalverification of each module in the Cadence HspiceS simulation environment. Thesimulation results show us that the functionality of the circuit has been realized，and theperformance of the circuit has reached the target.