Research And Design Of Driver And Protect Circuit For High Accuracy BUCK Converter

With the rapid development of modern electronic technique, the performance of portable electronic products is increasingly optimized. Portability as the obvious advantage of smart electronic products makes it to be the essential part of daily life. Being the core of electronic equipment, designing of supply confronts new challenge. For its high reliability、light weight、high efficiency and better anti-interference performance, switch power supply has been widely used in electronic facility. In order to fulfill the supply needs of all kinds of demand, it is quite necessary to have deep study in the optimization design of switch power supply. Furthermore, compared with other power management strategy, switch power supply show its superiority in efficiency(higher than 90%), which is in the line with energy conservation and the strategy of sustainable development. In switch power supply, the driver of power transistor plays an essential role in improving transfer efficiency; Over-temperature protection、under-voltage protection keep the chip in area of safe operation, which contributes to high reliability. Those works deserve to be deeply researched.Combing with the hotspot of switch power supply, the basic principle is analyzed firstly, the following is the advantages and disadvantages of different power supply structure, and finally put forward the DC/DC converter with constant on time control. At the starting point of driver block and protecting block design, lots of theory has been learned. Critical issue such as: dead time design、punch through protection has been dissected in driver block design. Meticulous analysis and simulation have been proceeded in soft start block、driver block、output voltage protection block、Over-temperature protection block designing.Finally, system verification was carried on by SPECTRE under the environment of CADENCE 5.1 based on 0.35 um BCD process. A BUCK system with the input voltage range of 4.5V~28V、minimum output voltage of 0.8V is accomplished, which is featured by fast transient response、high accuracy and high stability.