Research And Design Of Flyback Primary-side Feedback AC/DC Power Chip

As the heart of various electronic devices,power management chips are used in many fields such as automotive electronics,charging adapters,and the Internet of Things etc.The demand for power management chips in the electronics market is gradually developing towards higher efficiency,smaller size and higher reliability.The primary-side regulation converter is widely used because of its unique electrical isolation characteristics,higher reliability or safety,and it also avoids the use of optocouplers that are sensitive to environmental conditions,that reduces the number of chip peripheral components,effectively improves,the integration and stability of the chip.In recent years,PSR has become a research hotspot in power management chip designThis paper investigates and analyzes the working principle and low power consumption technology of primary-side feedback power management chips at home and abroad in recent years,and studies and designs a primary-side feedback AC/DC chip.The principle of PSR flyback converter and the realization principle of constant voltage and constant current function are introduced in detail.The main source of the sampling accuracy error of the PSR system is analyzed,and the sampling window auxiliary circuit and cutting-edge blanking technology are used to solve the inherent leakage inductance effect of the inductor and improve the sampling accuracy of the output voltage and current.The feedback voltage energy recovery structure is designed,and the feedback sampling voltage is used as the power supply branch of the chip power supply to improve the energy utilization efficiency and effectively reduce the power consumption.In addition,the chip core sub-circuit module includes a power supply module with comprehensive protection function,an oscillator module,a constant voltage control module,a constant current control module and a drive circuit module.A special high-voltage driving MOS that can be integrated inside the chip is used as the output power transistor to achieve safe high-voltage startup and improve the reliability of the chip.Through co-simulation verification,the design requirements have been met.This paper proposes a PSR flyback switching power supply AC/DC control chip with a maximum rated power of 10 W based on the SMIC 0.18 μm CMOS process.The chip includes Pulse-width Modulating（PWM）and Pulse-frequency Modulating（PFM）.The system simulation is completed by Cadence Spectre.The chip’s operating voltage range is 6-70 V,the operating temperature range is-60 °C to180 °C,and the adaptive frequency range is 10-100 k Hz.In the constant current mode,the maximum output is 2 A constant current;in the constant voltage mode,the system efficiency is 73% when the load is 100 m A,the efficiency is 77% when the load is 1 A,and the efficiency is as high as 87% when the load is 2 A.