Design Of A Flyback AC/DC Controller XD1403 With Constant Current And Constant Voltage Output

Since entering the information age, the development of electronic technology become much more rapidly, portable electronic products come into the household gradually. With the increasing consumption of resources and the improvement of people’s requirements of life’s quality, efficiency, energy-saving, lightweight, stability have become a new problem of electronic products, which is also the new direction of the designers need to consider. As the energy source of electronic products, power products are developing toward miniaturization, high efficiency and high stability, it is becoming the new challenges and opportunities for the development of power systems and products.This paper is based on the project ‘Small power Flyback AC/DC controller with constant current and constant voltage output’, which is from ultra-high-speed circuit design and electromagnetic compatibility ministry of education key laboratory of Xidian university. And according to the basic power supply topology and control theory of swithcing power supply, with high efficiency, high stability and practicality as the goal, combined with the specific application requirements of the chip, this paper has designed a high efficiency flyback AC/DC controller XD1403 with constant current and constant voltage output.This paper describes the design process of controller XD1403. Firstly, the paper reviewed the emergence and development process of the power system, and analyzed the current situation and develop trend of switching power supply, which provided direction for the design of the chip. Secondly, the paper analyzed the main topology and principle of the switching power supply, and a description and comparison of different modulation methods is given, so the topology and modulation method for XD1403 is determined. Thirdly, the paper designed the fuction of the module, the index parameters and the overall loop system, also analyzed the loop. Then the paper designed and analyzed the circuit of sub-modules, and simulation of the sub-modules is done. At last, the paper simulated the overall function of the controller XD1403.The controller can be used in electronic products’ chargers and LED drivrers. Compared with the traditional type of controller, XD1403 has the following advatages: Use auxiliary winding to collect output information on the secondary side, that can eliminate the need for optocoupler and TL431 and reduce the size and cost of the power system; The large charging resistor in tranditional flyback conterver is rounded, but XD1403 uses a high-voltage strart up circuit, which can improve the speed of charge time on VDD capacitor, and reduces the static powe consumption; Besides, the paper designed the protect function such as the input line under voltage protection, over temperature protction, undervoltage lockout and so on, it can make the chip more efficient and safe.The design of controller XD1403 is simulated accroding to the 0.5μm 5V/30V/700 V CMOS process, simulation results show that the performance of each module has achieved the target, and the controller’s application circuit achieves a high stability constant output of 5V/0.7A.