【作者】 程晓洁；

【导师】 冯全源；

【作者基本信息】 西南交通大学 ， 通信与信息系统， 2006， 硕士

【摘要】 大规模集成电路的飞速发展使得电子产品的体积越来越小,促使了便携式电子产品如雨后春笋一般蓬勃发展,不断添加的新特征和能力,使得电子产品变得越来越复杂,作为电子设备运作的核心—电源就面临了越来越大的挑战。LDO电源稳压器的低压差和低噪声特性使得它在便携式电子设备市场中具有不可替代的地位,因此研究并改善LDO的性能具有很大的意义。 除了性能要满足供电产品的要求外,电源自身的保护措施也非常重要,过流保护即是防止LDO因过载或输出短路造成意外损坏的防护措施之一。但是带一定过流保护功能的集成LDO电源稳压器容易出现闩锁问题影响其正常使用,也需要设计者给予完善。 在国家自然科学基金和四川省学术带头人基金的资助下我们对电源管理芯片进行了研究,我们首先分析了两种传统过流保护方法的功能及优缺点,在此基础上研究并提出了一种基于LDO的高性能的过流保护电路,该保护电路不仅可以可靠地保护芯片,还能降低系统功耗以及改善集成稳压器中的闩锁效应。通过在一般foldback电路中增加限流功能改变曲线的斜率,避免与负载曲线相交,从而解决稳压器的闩锁问题。本文还简单讨论了LDO的核心电路——放大器和PMOS调整管,仿真时结合这两部分电路来验证本文提出的过流保护电路的可行性。 利用CMOS工艺设计的电路容易缩减元件尺寸,增加MOSFET的速度,而且功耗低、制作成本也低,因此本文的过流保护电路就采用了0.6μm的标准CMOS工艺设计,达到了较好的性能指标。结合LDO的核心构架,利用Hspice仿真证明了该过流保护电路的可行性和可靠性。更多还原

【Abstract】 An increasing number of low voltage applications require the use of LDOs, i.e., cellular phones, pagers, laptops, etc. The motivation behind the study of the low dropout (LDO) regulators is driven by the increasing demand for higher performance power supply circuits.In regular use of LDOs, current limiting is one of the most desirable features for many LDOs against overload or inadvertent load shorts. So based on the analysis of two traditional protection methods, a low-power high reliability CMOS current limiting circuit is proposed, which can lower the circuit’s power dissipation and improve the LDOs’ latch-up effect which is an unexpected problem too. Latch-up effect can be avoided through combining foldback function with constant current limiting function which could change the slope of the foldback current curve to avoid intersecting the static load line.In the first part, this paper introduced the background and significance of this research. In the second chapter, two kinds of current limiting circuits were discussed. After that, on the basis of the prior knowledge, we successfully designed a current limiting circuit. This paper also discussed the circuit design considerations under different conditions of the major components of the regulator in existing process technologies, the pass device and the error amplifier.CMOS technology has been the mainstay in mixed-signal implementations because it provides density and power savings on the digital side, and a good mix of components for analog design. By reason of its widespread use, CMOS technology is the subject of this paper. The Hspice simulation results proved the feasibility of the circuit.更多还原