Research And Design Of Power Management Chip Based On The Flyback Structure

With the development of science and technology, requirement of electronic productshave also increased. The power supply become important in electronic equipment, and thepower supply develops towards high integration, high conversion efficiency, low powerdirection. Due to its superior performance, the switching power will replace the linearregulated power supply, and power management chips have become the mainstream of thepower development.Combined with the specific project, a flyback power supply AC-DC powermanagement chip has been designed. The flyback structure and PWM modulation modecontrol switcher are adopted. The main function modules include bandgap reference circuit,PWM circuit, oscillator circuit, and an overvoltage protection circuit, a clamping circuit,overcurrent protection circuit, thermal protection circuit for the system safe and stable. Tomake the power switch tube normal work, the soft start circuit, soft drive circuit andleading edge blanking circuit are designed. At the same time, integrated frequency jittermodule is applied to improve the EMI performance. The circuit function and some typicalperformance parameters are simulated and analyzed. The simulation results show that,when the operating frequency of the chip is65KHz, under light load conditions can enterthe burst working mode, low starting current is about3μ A, which effectively reduce thestart-up loss, and soft start time is about3ms.Based on1μ m40V high voltage BiCMOS process, the circuit layout is designed andverified. Finally, the fabricated chip has been tested, test results show that the chipperformance indicators meet the design requirements.