Design And Achievement Of Buck DC/DC Switch Model Converter

DC/DC switch mode regulator has been widely used all over the world for the virtues of high conversion efficiency and high integration. As the progress of integrated circuit technology, the peak current mode PWM DC/DC switch mode regulator with complex structure has become the mainstream of the market because of its better performance.This paper studies the basic principles of buck DC/DC converter and the topology. It focuses on the analysis of the buck DC/DC converters in a variety of modes of operation principle, and analyzes their respective advantages and disadvantages. Open-loop instability, slope compensation and frequency compensation of system is also investigated.This paper designs a buck DC/DC switch mode regulator with the BCD process. The peak current mode is used. Its clock frequency is 380 kHz with internal power MOSFET switch, with the function of under-voltage protection, over-temperature protection and over-current protection. In this paper, the main function modules of the converter such as: reference circuit, over-temperature protection circuit, comparator, error amplifier, oscillator circuit with the slope compensation circuit, driver circuit, under-voltage lockout circuit, and current sense amplifier are designed. Meanwhile, simulation researches are done for each cell in cadence and prospective value is achieved.Based on the application circuit of the converter, the tests are accomplished by the simulation software-Hspice. The results show that all of the electrical characteristics can meet the specifications. The converter is characterized by 23μA shutdown mode, its efficiency can reach 95%. It can be used Distributed Power Systems, DSL modems, battery chargers, and so on. The design chip has been taped out with a BCD process, the corresponding layout area is 1.3μm×1.3μm.