电池电量计和充电器芯片DS2770的原理及应用

DS2770是Dallas Semiconductor公司生产的一款电池电量计和锂/镍化学电池充电器集成器件，它可以通过1-Wire接口与主系统进行通信，以读取电压、温度等测量信息，同时读写EEPROM存储器，因而可广泛应用于便携式设备中。     

DS2770 Li+电池脉冲充电器与线性充电器的性能比较

脉冲充电器具有许多与线性充电器相同的优点,如:简单、廉价、小尺寸、外部元件少等。与线性充电器相比,脉冲充电器还具有一些独特的优势,它的热量主要耗散在墙上适配器、而不是充电器本身,由此,设计中不需要考虑散热问题。当然,它也存在某些缺陷,按照传统的观点,Li+电池脉冲充电器可能导致电池过早地老化,这一结论是以恒流充电过程和脉冲充电过程采用了相同的充电电流为前提的。利用DS2770构成的脉冲充电器进行一系列测试后,所得数据与传统观点并不相符。本文对线性充电器(CC/CV)和DS2770电池监视与脉冲充电器的测试数据进行了比较,主要…     

低成本的SOT-23锂离子电池充电器

LTC(?)1734是一种低成本、具有恒压及恒流控制的单节锂离子电池充电器。少数量及廉价的外部元件使整个系统成本非常低,再加上采用6引脚SOT-23封装,使得该IC可提供小巧的设计解决方案。早先的产品通常需要外部电流检测电阻和阻塞二极管,现在这些功能都被集成到LTC1734内。其它特性包括:     

高集成度、低成本电池充电器

1 锂电池充电方式概述 常用的二次电池有镍镉电池,镍氢电池,锂电池等多种类型.以目前在便携式数码产品中最为常见的锂电池为例,锂电池具有较高的能量密度,体积小,重量轻,寿命长,无记忆效应以及不污染环境等诸多优点,因此广泛应用于数码设备中,经济实用,而且灵活方便.     

DS2726在充电器反接时保护Li+电池的应用

简要介绍DS2726主要特性以及引脚功能.在DS2726典型应用电路的基础上,通过简单设计修改,可利用DS2726 Li+电池保护器承受负压,在充电器反接时为电池提供保护.     

DS2726在充电器反接时保护Li＋电池的应用

简要介绍DS2726主要特性以及引脚功能。在DS2726典型应用电路的基础上,通过简单设计修改,可利用DS2726U＋电池保护器承受负压,在充电器反接时为电池提供保护。     

自制限压保护型充电器

收音机、单放机等小家电常采用镍镉电池供电,常规的充电方法是:从家用电器取出电池,放入专用充电电器充电,充足电后再装入电器使用。这样取出、装入极不方便。如果在充电器输出端焊接一插头,通过电器的电源插座对电池直接充电,即可避免电池取出装入的麻烦。但由于充电器常根据镍镉电池的性能设计为恒流充电,一旦电器内部电池接触不良,如果不慎打开了电器开关,当电器工作电流小于充电电流时,会使加在电路两端的电压升高,将对电器造成危害甚至于损坏。为此,笔者设计制作了这款限压保护型充电器。工作原理:电路如附图所示。变压器T、D1～D4、C1为整机提供     

PF-12智能型充电器

PF-12智能型充电器是WATTAGE公司的一款产品。这一产品有以下特点:1、充电器既用于对镍镉(Ni-Cd)可充电电池充电,也适用于对镍氢(Ni-H)可充电电池充电。2、充电器可为4节至12节串联可充电电池充电。3、充电器采用恒流方式充电。输出电流可在250mA至2A之间连续可调,这样可以实现     

DS2711／DS2712镍氢电池充电器

锂离子电池是目前比较理想的可充电电池，但并不意味着它可以淘汰其它化学电池。像镍镉（Nicd）和镍氢（NiMH）电池，因其坚固，能承受较高的放电速率，具有较长的使用寿命，不需要特殊的保护电路，并且价格便宜，故在可充电电源系统中仍拥有自己的优势。由于镍镉电池容量低，含有有毒的镉元素，正在被镍氢电池所取代。镍氢电池及其充电器仍有较大的市场需求。     

DS SSMA with some IC realizations

A direct-sequence spread-spectrum multiple-access (DS SSMA) system was examined, realized (hardware), and tested. Essentially, two transmitters were built: one had voice capability, whereas the other transmitted only binary data. Gold codes were used for the spreading sequence. The PN synchronization used a serial search technique for acquisition, and a tau-dither loop for tracking. A squaring loop and a differential encoding scheme (for carrier phase ambiguity) was used in the demodulation process, which was followed by conversion to a voice output when desired. The system was found to perform quite well under both single and multiple-access conditions. As a demonstration of the feasibility of implementing the system on chips, a few small blocks were put on ICs using CMOS technology. These performed as expected, and clearly demonstrated both the feasibility and attractiveness of a VLSI implementation     

用软件控制DS 1620 实现高精度温度测量

简要介绍了数字温度传感器DS 1620的特点及其基本工作原理,给出了利用DS 1620实现高精度温度测量的方法、关键技术和软件流程图.     

带VCC输入引脚的硅序列码芯片DS2411及其应用

DS2411是Dallas Semiconductor公司推出的一种典型的一线式低成本电子识别码芯片。该器件带有外部电源输入引脚，可直接连接到微处理器的一个信号端口来进行高于15．4kbps速率的数据通信。文中介绍了DS2411的主要特点和引脚排列，重点给出了DS2411的应用设计方法。     

A Synchronous DS4 Multiplexer with Cross-Connect Function

The development and system design of a new synchronous DS4 multiplexer with cross-connect function is described. This new multiplexer is expected to provide cost reductions due to more efficient use of transmission facilities, and rapid circuit provisioning. The multiplexer consists of three kinds of digital cross-connect blocks, a transmission terminating block, an intraoffice-interface block, and a controler. It is also expected to provide improved network maintenance, higher network reliability, and greater system versatility for new services.     

干扰和噪声环境中直扩信号的截获

直扩（DS）信号功率谱密度（PSD）低,通常伴有干扰,因此在截获其中的信息时,需要把干扰也考虑在内,为此,提出了一种方法,充分利用直扩信号的特点和梳状滤波器的特殊频率响应特性,在小信噪比和小信干比的情况下有效截获直扩信号中的扩谱码,从而截获信息。     

射频供能传感网能量源移动路径约束下时延最小化供电方案

射频能量捕获技术是解决传统无线传感网由于节点电量有限而生命周期受限的有效方法。现有的射频能量源移动供电方案中,能量源可以无限制地沿任何方向行进到网络区域内的任一位置来给节点供电。然而在现实场景中,能量源通常只能沿着既有道路行进。考虑能量源行进路径约束下的供电总时延最小化问题,分别提出全程移动供电方案和部分位置停留供电方案,并提出高效算法来确定这两个方案的最佳行进路径和供电时间。仿真结果表明,两种方案的供电总时延均显著优于转折点供电基准方案。相比于部分位置停留供电方案,全程移动供电方案的计算复杂度较低,但供电总时延更长一些。     

On rate-variable multidimensional DS/SSMA with sequence sharing

A general model for M-ary direct sequence-spread spectrum (DS/SS) communications is presented to provide multiple services in direct sequence-spread spectrum multiple access (DS/SSMA). The main idea is to allow each user to use parallel orthogonal spreading sequences, depending upon its needs. More specifically, each service level is associated with certain combinations of the sequences. We use a code, which we refer to as a “mapping code”, to form a multidimensional signal constellation. Thus, the data rate can be changed by changing the mapping code. Further, techniques of sequence sharing (reuse) and sequence arrangement (allocation), suitable for packet switching, are proposed; this allows support of multimedia services, while resulting in a reduction of sequence consumption. We evaluate error rates in the presence of multiple access interference (MAI) and additive white Gaussian noise (AWGN). Numerical results are given to show the effects of the system configuration, the data rates, and other system performance measures     

DS/CDMA closed-loop power control with adaptive algorithm

Closed-loop power control in the reverse link of a DS/CDMA system is analysed. The transmitter/receiver based on IS-95 and the radio propagation channel under mobile communication environments are modelled and a new power control algorithm is proposed. This algorithm utilises the burst error characteristics of the channel and can be directly applied to the current IS-95 system. The new power control algorithm, with respect to the SIR (signal to interference ratio), increases the service quality, and finally, enhances the system capacity     

Thermoelectric Properties of Sb2Te3-Based Nanocomposites with Graphite

Semiconductors - Antimony-telluride-based nanocomposite samples containing different weight fractions of graphite (Sb2Te3 + x% graphite, where x = 0.0, 0.5, 1.0, and 2.5%) are synthesized and...