电流模式DCDC降压控制电路的设计

PWM电流模式DC-DC降压控制电路的设计

当今消费市场中，便携式电子产品所占比重较大，这种产品要求电池体积小、重量轻、使用时间长。高效、低压开关DC-DC转换器，通过提高电源转换效率及改进控制技术，达到了所需要求，因此被广泛应用于电子产品中。

本文首先介绍了Buck DC-DC转换器的拓扑结构及工作原理，并且详细论述了两种工作模式。然系统的设计与分析，具体介绍了电流感应电路、过流保护电路、带斜坡补偿的振荡器以及同步整流驱动电路等系统关键模块的设计与仿真。其中，振荡器电路的设计中，利用一种简单的斜坡补偿电路，完成了窗口比较式振荡器的充放电电路的功能，具有简洁高效的特性。

同时，在模块电路设计中，采用0.35µm工艺，从功率级设计开始，详细讨论了元件类型的选择以及电路结构参数的确定。之后，配以简单的外围电路构成了Buck DC-DC转换器系统，并对其进行了功能仿真，Hspice仿真结果表明，该系统能稳定工作，并满足设计指标的要求。

关键词：PWM峰值电流模式；Buck DC-DC转换器；带斜坡补偿的振荡器

Title：DESIGN OF CURRENT-MODE BUCK DC-DC CONVERTER CONTROL IC

Major：Microelectronics and Solid Electronics

Name: 李强Signature: Supervisor: Associate Prof. Lu Gang Signature:

Abstract

In today’s consumer market, battery-operated portable electronic devices are in great demand. For these devices, small size, light weight, and long battery run-time are the main demands. The highly efficient low-voltage switch-mode DC–DC

converters are mandatory in these devices for minimizing the size and weight and

extending the battery run-time, by enhancing the efficiency of power supply and

improving the control technology.

The topology structure and basic principle of buck DC-DC converters are

introduced firstly. Meanwhile, two operation modes are depicted in detail. Then the

whole system is designed and analysis. And the key modules, such as current sensing circuit, over current protection circuit, and synchronous rectifying driver, are designed

and modulated. A simple slope compensation circuit is used to substitute for charging

and discharging capacitor in the window comparator oscillator. And the oscillator is

simple and effective.

In the module design part, starting with the power stage, the type and parameters selection of electronic devices are discussed. Finally, a whole Buck DC-DC converter system, which can be completed by the control IC with few external parts,is

simulated by Hspice, with 0.35µm CMOS process, whose results indicate that the

system is stable and circuit function and performance have perfectly satisfied the

design requirements.

Key words: PWM peak current-mode control method; Buck DC-DC converter;

oscillator with slope compensation circuit 1

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