一款电流模同步升压型DC-DC转换器XD1407的设计

发布时间：2018-10-12 14:35

【摘要】：本论文以设计高性能芯片为目标,结合当前需求,在以西安电子科技大学的科研项目“电源管理类集成电路关键技术的理论研究与设计”的基础上,设计了一款DC-DC转换器XD1407。论文首先对开关电源进行了介绍,然后结合当前市场情况,分析了开关电源的核心组成部分DC-DC转换器的重要性及发展趋势;接着详细阐述了直流转换器的基本理论知识和工作过程,并对升压型DC-DC转换器的控制方式及效率进行了仔细研究,结合本芯片的特点,选取合适的控制方式即电流模式,同时提出了提高效率的解决方案;然后对芯片XD1407整体架构进行了分析与设计,针对该芯片的环路稳定性进行系统性建模,推导了该芯片在工作时的零极点位置,并对本芯片的稳定性作出了仿真验证;继而对芯片XD1407的关键模块进行电路设计与仿真验证,验证结果均符合设计要求;本论文的最后一章是对芯片XD1407整体电路仿真结果的介绍。升压型XD1407的工作频率为500kHz,固定不变,采用峰值电流模式控制,内置功率开关管和同步整流管,使其在应用时外围电路简单化,节省PCB面积;XD1407工作电压范围为2.5V-5V,在该工作范围内峰值电流为8A,带载能力可以达到5A;芯片内部设计了软启动电路,有效防止了因输出电压或电感电流的过冲对芯片造成的损害;XD1407有两种工作模式即PWM模式和轻负载模式,当负载较小时,通过检测电感电流信息判断该芯片工作于轻负载模式,该模式下芯片在连续工作几个周期后,可进入休眠状态,休眠期间,主开关管和同步管都不能导通,将芯片内部大部分模块关断,使芯片的静态电流降低,减小到55u A,此时导通损耗及开关损耗可以几乎为零,输出电压开始下降。电路中通过检测反馈电压FB来控制输出电压的下降量,利用高精度比较器输出脉冲控制信号,通过逻辑电路的处理后控制芯片退出休眠状态,如此反复工作;随着负载的逐渐增大,电感电流随之升高,该芯片转换为PWM工作模式,两种工作模式之间可平滑切换,保证该芯片在整个负载范围内均可以得到较高的转换效率,同时具有较小的输出电压纹波;通过对升压型DC-DC转换器的仔细研究,然后结合理论知识进行建模分析,确定该芯片的频率补偿方案,通过调节相关参数,利用仿真软件选择合适的带宽频率和相位裕度,使系统环路可以稳定工作。XD1407内部同时设计了多种保护机制,使芯片在输入电压较低、过高温度和过高电压等条件下不被损坏。XD1407基于某公司的0.35 u M CMOS工艺,利用Cadence软件进行仿真验证,确保仿真结果在不同的器件模型,不同电源以及温度下均可达到设计要求。仿真验证的结果表明芯片的各方面性能良好,满足了设计要求。
[Abstract]:Based on the research project of Xi'an University of Electronic Science and Technology, "theoretical research and design of power management integrated circuit", a DC-DC converter XD1407. is designed in this paper, aiming at the design of high performance chip. This paper first introduces the switching power supply, and then analyzes the importance and development trend of the DC-DC converter, the core component of the switching power supply, according to the current market situation. Then the basic theoretical knowledge and working process of DC converter are described in detail, and the control mode and efficiency of boost DC-DC converter are studied carefully. According to the characteristics of this chip, the appropriate control mode is chosen, that is, current mode. At the same time, a solution to improve efficiency is proposed, and then the overall architecture of the chip XD1407 is analyzed and designed, the loop stability of the chip is systematically modeled, and the zero pole position of the chip is deduced. The stability of the chip is verified by simulation, and then the key modules of the chip XD1407 are designed and verified, and the results meet the design requirements. The last chapter of this paper is the introduction of the overall circuit simulation results of the chip XD1407. The working frequency of the boost type XD1407 is 500kHz, which is fixed and invariable. It adopts peak current mode control, built-in power switch and synchronous rectifier, which makes the peripheral circuit simple when it is applied. The PCB area is saved, the working voltage range of XD1407 is 2.5V-5V, the peak current is 8A and the load capacity can reach 5A. XD1407 has two working modes, PWM mode and light load mode. When the load is small, it can be judged that the chip works in light load mode by detecting the information of inductance current. In this mode, the chip can be put into dormancy state after several cycles of continuous operation. During the dormancy period, the main switch tube and the synchronous tube can not be switched on, so that most of the modules inside the chip are turned off, so that the static current of the chip is reduced. When reduced to 55 U A, the conduction loss and switching loss can be almost zero, and the output voltage begins to decrease. In the circuit, the output voltage drop is controlled by detecting the feedback voltage FB, the pulse control signal is output by the high-precision comparator, and the control chip exits the dormant state after the processing of the logic circuit, so it works repeatedly. With the increasing of the load, the inductance current increases, the chip is converted to PWM mode, and the two modes can be switched smoothly, which ensures that the chip can get higher conversion efficiency in the whole load range. At the same time, it has small output voltage ripple, through the careful study of booster DC-DC converter, then combined with theoretical knowledge to model and analyze, determine the chip frequency compensation scheme, by adjusting the relevant parameters, Using the simulation software to select the appropriate bandwidth frequency and phase margin, the loop of the system can work stably. A variety of protection mechanisms are designed in XD1407 at the same time, so that the input voltage of the chip is low. XD1407 is based on a company's 0.35 u M CMOS process and is verified by Cadence software to ensure that the simulation results can meet the design requirements under different device models, different power supply and temperature. The simulation results show that the chip has good performance and meets the design 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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