PPTC保护器件在无线电子产品中的应用

无线电子市场的蓬勃发展对电路保护提出了新要求，这是因为数字器件对过大的电流或者过高的电压变得更加敏感。由于锂电池的发展，以及电池充电技术的广泛应用，新的PPTC(聚合物正温度系数)保护器件应运而生。PPTC保护器件的性能好，体积小，对于要求元器件尺寸很小、重量很轻的产品是极为重要的。     

额定线电压PPTC器件帮助保护电器电机和变压器

现在广受欢迎的PPTC高分子正温度系数可复位电路保护器件推出了额定线电压系列，为家用电机和专业电机保险丝和双金属保护装置提供了简单而具有成本效益的另一选择。     

浅谈PPTC电路保护元件

自复保险丝是近几年出现的新型正温度系数过流保护元件,英文名称为“Polyswitch”,即高分子聚合物开关之意,主要用于小功率电子设备的短路及过载保护。与传统保险丝相比,其可恢复功能无与伦比,并且这种恢复过程可重复数千次。PPTC电路保护元件典型的应用包括计算机外设、电信设备、二次充电电池、电源、汽车电子及变压器等。PPTC工作原理以美国瑞侃公司的自复保险丝为例进行说明。如图1(a)所示,自复保险丝主要以经过特殊处理的聚合树脂(Polymer)为基础,掺入导体而构成。在正常情况下,聚合树脂将导体微粒紧密束缚于结晶状的结构内,构成一…     

可复位保护元件在汽车网络中的应用

介绍IDB-1394网络结构及外设电路保护要求，给出可复位保护电路在车电子系统中的应用及PPTC保护电路元件的选择原则。     

PPTC保护器件在电源转换器中的应用

PPTC电路保护器件在电流浪涌过大、温度过高时起保护作用。和传统的熔断丝一样,在出现故障时,这种器件能够限制危险的大电流。不同的是,在排除故障、撤除电力之后,PPTC保护器件可以恢复原来的状态,从而可以降低产品保修、服务及修理的成本。PPTC的应用包括无线产品、可充电电池、充电器以及AC/DC电源转换器。     

PPTC组件在锂离子电池组短路及过充电保护中的应用

随着对便携式设备更长运作时间、小尺寸及重量等需求日增,促使业界不断朝体积更小、更轻的锂离子及锂聚合物电池发展,同时要具备更高能量密度与更快的充电速率。由于数字无线电话、数码相机等对脉冲电流供应的需求增加,电池充电速率与内部阻抗也成为重要课题。电池化学物具有较高的能量密度与充电速率,使电池电路保护设计变得很复杂。 以二次充电锂化学物为基础的电池和电池盒,对过电流/过温状态特别敏感,这种状况是由意外短路、滥用或难以控制的充电所致,使电池温度升高,导致电池受损或设备故障。当金属物体(如笔记本用蝴蝶夹或钥匙环)连接…     

功率电子的电路保护新选择

在线性变压器或电源出现故障时，某些元器件会产生过热现象。在开关型充电器发生故障的情况下，一些可能随之出现故障的元器件包括磁性元件或开关场效应管。在线性充电器中，没有场效应管或电子线路进行功率转换，变压器的线圈是最有可能出问题的器件。     

提供电路保护功能和降低维修成本的聚合物PTC组件

PPTC组件不但提供了自复式的电路保护功能，而且相较于只能使用一次的普通保险丝，它还拥有许多其它的优点。     

手持终端设备电源管理系统的PPTC电路保护

着重介绍Raychem电路保护部的PolySwitch PPTC（聚合物正温度系数）元件在电源管理中提供电流过载和温度过载的保护过程。另外还介绍了电源适配器、CLA（点烟器）、移动电话设备及电池板的保护装置是如何进一步改善实际使用中的总体可靠性的。     

PPTC过流保护的应用

本文介绍PPTC过流保护在便携式电子设备、电流电配器和充电器中的应用。便携式电子设备保护便携式电子设备，例如蜂窝电话、PDA和手提电脑的电源都有特殊的过流保护要求。这些设备一般是通过AC/DC电源适配器供(充)电，将市电或未经稳压的直流电转变为合适的低压直流电。由于越来越多的人开始在零配件市场上购买电源适配器以及通用充电器，将不兼容或有故障的电源适配器应用于便携式设备的可能性也就大大增加。由于电源适配器的电压、极性以及电流都可能与该设备的电路规范不相吻合，从而将会导致损坏甚至带来安全隐患。体积小，熔断保…     

协同电路保护有助于防止DVB网络设备的损坏

信息产业部软件与集成电路促进中心与Tensilica公司签约建立“信息产业部软件与集成电路促进中心-Tensilits联合实验室”。合作双方将依托实验室为广大企业提供培训服务，推广可配置处理器技术，同时将提供面向企业的Tensilica自由评测相关业务和SoC设计支持，为企业提供特惠MPW服务，以及以IP团购方式为企业提供优惠IP交易．     

SiGe材料及其在半导体器件中的应用

介绍了SiGe材料的发展历史、特性、制备方法及其在半导体器件中的应用。     

Two-photon laser precision microfabrication and its applications to micro-nano devices and systems

Two-photon absorption (TPA) provides the ability to confine photochemical and physical reactions to the order of laser wavelength in three dimensions. For applying TPA to laser precision microfabrication, we proposed a two-photon photopolymerization technique, by which photonic crystals and various micromachines with near-diffraction-limit features have been produced. Here we show that the diffraction limit was exceeded by utilizing nonlinear laser-matter interaction processes, and spatial resolutions far smaller than the diffraction limit were achieved. The super resolution, combined with other technologies newly developed by us including three-dimensional imaging of voxels, rapid surface profile scanning, device functionalization and its mechanical driving with a laser trapping force, and dye-doping polymerization for three-dimensional microdiagnosis, makes the technique quite compelling for nanophotonic and optical microelectromechanical (MEMS) applications.     

Single-electron devices and their applications

The goal of this paper is to review in brief the basic physics of single-election devices, as well as their-current and prospective applications. These devices based on the controllable transfer of single electrons between small conducting “islands”, have already enabled several important scientific experiments. Several other applications of analog single-election devices in unique scientific instrumentation and metrology seem quite feasible. On the other hand, the prospect of silicon transistors being replaced by single-electron devices in integrated digital circuits faces tough challenges and remains uncertain. Nevertheless, even if this replacement does not happen, single electronics will continue to play an important role by shedding light on the fundamental size limitations of new electronic devices. Moreover, recent research in this field has generated some by-product ideas which may revolutionize random-access-memory and digital-data-storage technologies     

Optical fiber-based devices and applications

Optical fiber technology has undergone tremendous growth and development over the last 40 years. Optical fibers constitute an information super highway and are vital in enabling the proliferating use of the Internet. Optical fiber is also an enabling technology which can find applications in sensing, imaging, biomedical, machining, etc. There have been a few milestones in the advancement of optical fiber technology. Firstly, the invention and development of the laser some 50 years ago made optical communications possible. Secondly, the fabrication of low-loss optical fibers has been a key element to the success of optical communication.     

TOPSwitch-GX开关电源器件

TOPSwitch-GX是美国Power Integrations公司的产品,TOP242-249是TOPSwitch-GX系列产品中可扩展功率、设计灵活、Ecosmart型集成离线式新型开关电源器件.本文阐述了TOPSwitch-GX的分类及性能特点和工作原理,并通过实例介绍了该器件在通用输入电源和微处理器远程开/关控制电路中的应用.     

Properties and applications of reflective-array devices

The use of reflective arrays in surface-wave devices has yielded new devices such as resonators in addition to an enlarged parameter range for devices such as radar pulse expanders and compressors. A number of different grating geometries, substrates, and types of reflectors have been employed in resonators, band-pass filters, filter banks, oscillators, and dispersive delay lines. Simple, yet accurate, models have been developed for design and analysis of reflection gratings in these applications. The major application of reflective arrays has been in radar pulse compressors wherein low spurious levels and precise phase and amplitude response have been achieved in devices with time-bandwidth products as large as 10⁴. Other signal-processing applications such as chirp-z transforms can exploit the large time-bandwidth products available in reflective-array devices.     

激光防护器材的研究现状及进展

本文对３０多年来出现的各种激光防护器材及其原理、性能进行了总结和评价;介绍了基于非线性光学理论的各种新型防护材料及其研究进展;指出了今后激光防护研究的基本方向     

New devices for millimeter-wave applications

The possibilities for future developments of mm-wave devices are reviewed. New concepts and extensions of presently available devices are considered concerning sources, amplifiers and mixing. We discussed such ideas as micro-cavity triodes unbedded in the semiconductor chip with first experimental evidence available.