电流模升压型DC-DC控制器XD1496的设计

发布时间：2018-01-27 04:04

本文关键词： Boost型DC-DC 同步整流电流模式环路增益　出处：《西安电子科技大学》2014年硕士论文　论文类型：学位论文

【摘要】：直流开关电源给人类的日常生活提供了很大的便捷,然而在人体安全电压范围内存在许多供电电压,而且工作频率也各不相同。为了使用同一个芯片,在只改变外围器件参数的情况下满足不同的供电电压和工作频率,本论文旨在设计一款输入电压范围广,工作频率可调,电感电流采样精度高,转换效率高的升压型直流转直流控制器。为此本芯片采用电流模同步整流技术。为减小芯片面积,减少高压器件的使用,芯片内部集成一个高压的线性稳压器为内部其他模块提供工作电压;为使工作频率可调,外置调整电阻,跟随阻值的增大频率成正比例增加;为扩大应用范围,采用片外采样电阻,通过改变采样电阻阻值设置相应的采样增益;为提高转换效率,两个外置的功率管都采用NMOS管。论文首先阐述了电源管理芯片的研究背景和概述,然后对几种常见的直流转直流转换器的拓扑结构进行了说明和原理分析,接着又介绍了功率管不同调制模式的区别,并着重分析了PWM和PFM两种调制模式的工作原理和优缺点,同时又介绍了电压模反馈环路和峰值电流模反馈环路的工作原理及对系统性能的影响。论文在给出功率管线性模型的基础上,结合峰值电流模环路将升压型转换器整个环路进行线性等效,然后详细推导出只和占空比有关的电感电流和输出电压的传输函数,最后给出系统的等效小信号流程图并推导出整个系统的环路增益。依靠环路增益合理设置补偿参数,方便分析环路稳定性。论文在理论分析的基础上对系统的核心子模块包括带隙基准电路、启动电路、可调频率振荡器、电流采样电路、负电流检测电路等进行了设计和仿真验证。最后给出了XD1496的电气性能参数和整体功能的仿真结果。芯片XD1496采用0.6μm CMOS工艺,依靠Cadence下的Spectre等EDA工具对系统整体功能和电气性能参数进行了仿真验证。仿真结果表明系统整体功能和电气性能参数指标均达到设计要求。芯片在3~30V输入电压范围内稳定工作,输出为19V、12V和5V三个典型应用时分别能达到2A、3A和4A的最大负载,并且可以根据外部负载的不同,工作在PWM模式或PFM模式,保证系统满足设计要求的转换效率。睡眠状态下,静态电流达到55μA,通过仿真计算,系统转换效率高至96%。芯片的工作频率在50kHz~1MHz范围内线性可调,且系统均能正常工作。依靠片外采样电阻,电感电流采样精度达到93%以上,同时系统内部具有过温、过压、过流等非正常工作模式保护电路。本芯片可广泛应用于笔记本电脑、移动电源、汽车电子和便携式医疗设备等系统中,既可以提高正常工作时的电源转换效率,又可以降低休眠状态下静态功耗,极大改善了电池的续航能力。
[Abstract]:DC switching power supply provides great convenience to human daily life. However, there are many power supply voltages in the safe voltage range of human body, and the working frequency is different. In order to use the same chip. In the case of only changing the peripheral device parameters to meet the different supply voltage and working frequency, this paper aims to design a wide range of input voltage, adjustable operating frequency, high precision of inductor current sampling. High conversion efficiency DC converter controller. For this purpose, this chip adopts current-mode synchronous rectifier technology. In order to reduce the chip area and reduce the use of high-voltage devices. A high voltage linear voltage regulator is integrated inside the chip to provide working voltage for other internal modules; In order to make the working frequency adjustable, the external resistor is adjusted, and the frequency increases in proportion to the increase of the resistance value. In order to expand the scope of application, the off-chip sampling resistor is adopted, and the corresponding sampling gain is set by changing the value of the sampling resistance. In order to improve the conversion efficiency, both external power transistors use NMOS transistors. Firstly, this paper describes the research background and overview of power management chips. Then several common DC converter topology structure and principle analysis, and then introduced the difference of different modulation modes of power transistor. The principle, advantages and disadvantages of two modulation modes, PWM and PFM, are analyzed emphatically. At the same time, it introduces the working principle of voltage mode feedback loop and peak current mode feedback loop and its influence on system performance. Combining the peak current mode loop, the whole loop of boost converter is linearly equivalent, and then the transfer function of inductance current and output voltage related to duty cycle is deduced in detail. Finally, the equivalent small signal flow chart of the system is given, and the loop gain of the whole system is deduced. The compensation parameters are set reasonably depending on the loop gain. On the basis of theoretical analysis, the core sub-modules of the system include bandgap reference circuit, starting circuit, adjustable frequency oscillator and current sampling circuit. The negative current detection circuit is designed and simulated. Finally, the simulation results of the electrical performance parameters and the overall function of XD1496 are given. The chip XD1496 uses 0.6 渭 m. CMOS process. The whole function and electrical performance parameters of the system are simulated and verified by EDA tools such as Spectre under Cadence. The simulation results show that the overall function and electrical performance parameters of the system are up to standard. Design requirements. The chip works stably in the input voltage range of 3V / 30V. The output of 19V 12V and 5V can reach the maximum load of 2A3A and 4A respectively, and can work in PWM mode or PFM mode depending on the external load. The conversion efficiency of the system is guaranteed to meet the design requirements. Under the sleep condition, the static current reaches 55 渭 A, which is calculated by simulation. The conversion efficiency of the system is up to 96. The frequency of the chip is linearly adjustable in the range of 50kHz ~ 1MHz, and the system can work normally. The precision of inductance current sampling is more than 93%. At the same time, the system has over temperature, overvoltage, overcurrent and other abnormal working mode protection circuit. This chip can be widely used in notebook computer, mobile power supply. In automotive electronic and portable medical equipment systems, it can not only improve the efficiency of power conversion in normal operation, but also reduce the static power consumption in dormant state, and greatly improve the battery life ability.
【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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