Design Of Flyback Primary-side Feedback Dual-module Power Management Chip

With the rapid development of portable electronic devices,power management chips have played a vital role as the heart of various electronic products.Flyback power supplies rely on their advantages of low power consumption,high efficiency,low cost,input and output isolation.It stands out from the crowd of switching power supplies,so the research on the flyback primary-side feedback power management chip has important theoretical research significance and practical application value.A control chip that is applied to the dual-mode flyback primary side feedback is designed.According to the function of the chip,it can be divided into a power supply module,a constant current module,a constant voltage module,a peak current detection module,drive module and a protection circuit module.It can be used for chargers,adapters and LED drivers of portable electronic devices.The chip works in discontinuous mode,and adopts the primary side feedback flyback topology structure.Compared with the secondary side structure,there is no need for optocoupler devices and precision voltage regulators,and the surrounding auxiliary circuits are omitted,making the system more concise and lighter;Constant current mode is used in the switching power supply for fast charging in the initial stage of work,and constant voltage mode for charging in the stable stage;PFM modulation mode will be used at light load to reduce the system standby power consumption effectively.Quasi-resonant control mode is used in heavy load to achieve soft switching by turning on at the bottom of the valley,which greatly reduces switching losses.These two modes provide a flexible solution for different loads;At the same time,the built-in line voltage compensation technology is adopted to realize the effective compensation of the voltage drop loss of the output current on the output cable;a pre-shutdown mechanism is added to the peak current detection module,which effectively improves the accuracy of the peak current of the primary side,and Protection circuits such as over-temperature,over-voltage,and short-circuit are added,which greatly improves the reliability of the chip.Based on the Spectre software,the power management chip and the internal individual module circuits designed in this paper are simulated and verified.The simulation results show that the internal power module provides a 5V startup voltage to generate a 1.2V reference voltage,a 3.7V chip internal power supply voltage and 0.1V?2.4V unequal reference voltage;in constant current mode,it produces 4/7 demagnetization time duty cycle and constant 2.4A output current;in constant voltage mode,it produces a fixed output voltage of 5V,and other performances also meet the chip design indicators.The layout design of the power management chip was completed using the FMIC 1.5?m BCD process.The layout passed the DRC and LVS verification and was submitted for tape-out.