PSR-precision Constant Current And Constant Voltage AC/DC Chip Design

In the modern society,switch power supply has been widely used in all kinds of electronic equipment as a kind of high efficiency, portable and universal power converter. Especially in today’s rapid development of modern portable dressing equipment, on the basis of the development direction of traditional including the high frequency,the high integration and the digital, the high efficiency, the small volume and the high power has become a new research focus in the new era.Research topic of this thesis is to design a monolithic AC/DC chip which is based on the PSR(Primary Side Regulation) model to realize the constant current and constant voltage working condition. The chip that can achieve high efficiency working mode has a 85 ~ 265 V input voltage range wide and has multiple mode switch conditions. It is widely used in mobile phones, personal medical devices, cameras, tablets, and other portable electronic products.This chip works in the PSR control mode by controlling the drive of external high 700 voltage power MOSFET, thereby the system eliminate the light coupling and simplify the secondary control circuit.As a result, it reduces the cost while greatly simplifies the circuit design of the chip. A new type of constant current and sampling control method is implemented in the chip which omit the original inductance compensation and get the high precision of constant current working status at the same time.While,the soft driver technology is appended in the system to optimize the EMI.Besides,a series of protection measures is added in the system,for example over temperature protection, over-voltage/under-voltage protection, short circuit protection, open loop protecttion, the detection and protection of the line voltage and so on.The thesis firstly compares the basic working principle of the vice control and the PSR control topology and introduces the development status and prospects of the PSR control technology. Then introduces the circuit design steps of the peripheral system gradually. Finally introduces the working principle of the several modules in the systerm. The several key modules including the bandgap, the oscillator,the samplingcircuit and etc are simulated and analyzed in the thesis, while list the system simulation results which complete the verification of design goals at the last.