A Pwm Mode Research And Design Of The Flyback Switch Power Supply

Accompanied by the development of low-power consumer electronics, lighting, communications and other industries, the growing power converter industry, the switching power supply market demand is increasing, especially in AC/DC switching power converters to high-profile. Mobile class power and low voltage circuits widely used in AC/DC converters market growing, and its design to achieve the more stringent requirements.First by reviewing the technical background and development in switching power supply, its topology classified and described;and several common control modes in-depth analysis, and then present the flyback pulse width modulation switching power supply systemarchitecture. Followed by a continuous mode flyback pulse width modulation switching power supply infrastructure and non-continuous operating mode signal analysis, the flyback pulse width modulation switching power supply main parameters of the system loop design optimization, and in accordance with its small-signal model for the loop design of the pole-zero compensation circuit, the output filter capacitor ESR zero compensation network of high-frequency pole offset. Completed according to design specifications for system loop compensation circuitry, the oscillator circuit, leading edge blanking circuit, the slope compensation circuit and overload protection circuit sub-module circuit design. Finally, to complete the integration of the chip within the sub-module, and if possible, simulation, based on the practical application of the overall circuit design simulation circuit.Simulated with the0.35μm BCD process, the designed circuit simulation of each case, the AC input voltage is90V～264V, temperature range-40℃～125℃circuit output indicators are normal. Among them, the stability of the switching frequency of50kHz±1%of range, leading edge blanking time of270ns～330ns, and the delay time of320ns～530ns, load heavier within50ms±5%overload restart the chip.