Research And Design Of The Timer Circuit In The Switching Power Supply Of AOT Architecture

In recent years,with the development of networking technology and wearable devices, Consumer demand for portable electronic products is growing, however, Any electronic products once left the power will become a decoration. It is enough to show the importance of power equipment, the better performance of electronic equipment, the power of the index requirements are more demanding. Switching power supply with high conversion rate, small size, high reliability, anti-interference ability, etc, quickly become the mainstream products in the power market, by more and more designers attention.The traditional voltage control mode and current control mode are limited by the error amplifier, loop compensation network and other factors, making the system difficult to achieve fast transient response. Adaptive On-time control mode has the advantages of simple loop control, fast response speed, which makes it become the research focus of switching power supply. Timer circuit as the core module of AOT switch power supply, it is very important to connect analog part and digital part of the bridge. The main research work of this paper is to design a timer circuit which is suitable for the AOT architecture, which is used to generate the constant time for power switch tube and the stable output frequency without the change of the input and output voltage.Firstly, the basic knowledge of power supply technology, research background and significance, research status at home and abroad as well as the development trend of switching power supply are introduced. Then, the basic principle and control mode of the DC-DC BUCK converter are summarized, Further analysis of the basic principles of the timer circuit in AOT architecture,including the working characteristics and the loop analysis.Then it analyzes the structure of the timer circuit, and on this basis, the timer circuit is designed in this paper, and one of the sub-circuit function modules design and simulation analysis, and the sub circuit modules which are design and simulation analysis, Specifically:designed a three-stage comparator circuit in order to improve the circuit gain; in order to eliminate the influence of the transistor gate source voltage VGS, the compensation circuit is added to the design of the circuit in the time generating circuit; the feedforward technology is used in the design of the reference potential circuit, which makes the system’s ability to resist risks.Finally, added the timer circuit into the AOT structure buck converter to function- al verification. met the target set expectations.This article uses the candence software to carry on the circuit design, uses the hspice software to carry on the circuit simulation.