一款高效峰值电流模Buck型DC-DC转换器XD1408的电路设计

发布时间：2018-04-25 21:34

本文选题：开关稳压电源 + 降压型　；参考：《西安电子科技大学》2014年硕士论文

【摘要】：随着电子行业的快速发展,电子器件也越来越多地出现在人们的生活和工作当中,而且这些电子器件全部需要供电才能正常工作。开始只是些简单的电子器件被供电,但随着电子器件的不断精密化和小巧化,供电的技术要求也越来越高,由此便促使电源的供电技术向更高要求、更多功能发展,多种供电技术应运而生,其中就有开关稳压电源技术。虽然开关稳压电源兴起较迟,但是它的诞生极大地改变了世界的面貌。许多科技领先的组织和国家都投入大量的精力来推动开关稳压电源的发展。1990年后,开关稳压电源在多种场所飞速发展,笔记本电脑、手机和相机等便携电器都使用了开关稳压电源来供电,而保证这些电器的室外使用时间至关重要。在电池体积、容量固定的基础上,如何提高电源转化效率成为电源供电技术人员需要解决的问题。本文首先介绍了开关稳压电源的相关概念,包括它的基础知识和发展动向,并且主要对开关稳压电源中的降压型拓扑结构的相关理论进行了研究,然后设计了芯片内部的各个模块,包括主线模块和保护模块,并给出部分模块的理论依据以及仿真结果,紧接着分析了系统的环路稳定性并对其进行补偿,最后选取芯片XD1408的外部电路元器件并对整体系统进行了仿真验证。芯片XD1408使用峰值电流模式架构,它的目的是提高电路的敏感度,响应速度快,对每个周期的电感电流都有限制,而且本身也具有了过流保护功能;芯片XD1408还内嵌了软启动模块,不同于传统的设计方法,该方法用电阻替代了大面积的充电电容,采用数字逻辑,一步一步提高模块输出电压,并且提供一定的余量,它能很好地抑制芯片在启动过程可能出现的电流浪涌现象;在负载短路时,芯片会自动使主频率降到100k赫兹,从而使电感电流下降的时间足够长,防止出现失控情况;在停机状态时,流过芯片的电流会降至1μA或更低;为了使该芯片稳定安全地工作,它内部还集成了过压、过流、过热等保护模块。芯片采用同步整流技术,无需肖特基二极管,不仅节省了成本,而且提高了转换效率;芯片XD1408拥有宽的输入电压范围,可从2.5V~5.5V之间取值;它的主频率是1.5M赫兹,高频率的优势在于可以选择较小的电感,就能达到低纹波输出电压;为了减小系统在待机时功耗,芯片XD1408还设计了一种‘间歇工作模式’,也就是说当芯片工作在重载时,使用PWM模式;当负载降低时就会自动切换到间歇模式,也叫做Burst Mode,芯片效率都会很高。芯片XD1408仿真采用的软件工具是Cadence,仿真器是Hspice,所用的工艺是0.5μmCMOS模型,系统整体的仿真结果表明:电路的设计能够达到指标要求。
[Abstract]:With the rapid development of electronic industry, electronic devices appear more and more in people's life and work, and all these electronic devices need power supply to work properly. At first it was only simple electronic devices that were powered, but with the continuous refinement and miniaturization of electronic devices, the technical requirements for power supply became increasingly high, which prompted the power supply technology to develop to higher requirements and more functions. A variety of power supply technologies emerge as the times require, including switching power supply technology. Although switching power supply is late to rise, its birth has greatly changed the face of the world. Many scientific and technological leading organizations and countries have invested a lot of energy to promote the development of switching power supply. After 1990, switching power supply developed rapidly in many places, notebook computers, Portable appliances, such as mobile phones and cameras, use a switching power supply to power them, and it's important to keep them outdoors. On the basis of the fixed volume and capacity of the battery, how to improve the efficiency of power conversion has become a problem to be solved by the power supply technicians. This paper first introduces the related concepts of switching stabilized power supply, including its basic knowledge and development trend, and mainly studies the related theory of the step-down topology in switching stabilized power supply. Then every module inside the chip is designed, including the main line module and the protection module, and the theoretical basis and simulation results of some modules are given. Then, the loop stability of the system is analyzed and compensated. Finally, the external circuit components of chip XD1408 are selected and the whole system is simulated. The chip XD1408 uses peak-current mode architecture, which aims to improve the sensitivity of the circuit, the response speed is fast, the inductance current of each cycle is limited, and the chip XD1408 also has the function of over-current protection. Different from the traditional design method, the method uses resistance instead of a large area of charging capacitance, digital logic, step by step to improve the module output voltage, and provide a certain margin. It can restrain the current surge which may occur in the starting process of the chip, and when the load shortens, the main frequency of the chip will automatically drop to 100 kHz, so that the inductance current will fall long enough to prevent runaway. At downtime, the current flowing through the chip will be reduced to 1 渭 A or less. In order to make the chip work stably and safely, the internal protection modules such as overvoltage, overcurrent and overheating are also integrated. The chip uses synchronous rectifier technology without Schottky diode, which not only saves cost, but also improves conversion efficiency. The chip XD1408 has a wide input voltage range, which can be measured from 2.5V~5.5V to 2.5V~5.5V. Its main frequency is 1.5m hertz. The advantage of high frequency is that the low ripple output voltage can be achieved by selecting smaller inductors. In order to reduce the power consumption of the system while standby, the chip XD1408 has also designed a 'intermittent mode of operation, that is, when the chip is working in heavy load. PWM mode is used; when load is lowered, it automatically switches to batch mode, also known as Burst mode, and chips are highly efficient. The software tool used in chip XD1408 simulation is Cadence, the simulator is Hspice.The process is 0.5 渭 mCMOS model. The simulation results of the whole system show that the circuit design can meet the requirements.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM46

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