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Handheld electronic devices play a key role in our everydaylives. Because dependability is paramount, handhelds arecarefully engineered with lightweight power sources forreliable use under normal conditions. But no amount ofcareful engineering can prevent the mistreatment theywill undergo at the hands of humans. For example, whathappens when a factory worker drops a bar code scanner,causing the battery to pop out? Such events areelectronically unpredictable, and important data storedin volatile memory would be lost without some form ofsafety net—namely a short-term power holdup systemthat stores suffi cient energy to supply standby power untilthe battery can be replaced or the data can be stored inpermanent memory.
標(biāo)簽： 超級(jí)電容器 備用電源 手持設(shè)備
上傳時(shí)間： 2013-11-05
上傳用戶：coeus
A recent trend in the design of portable devices has beento use ceramic capacitors to filter DC/DC converter inputs.Ceramic capacitors are often chosen because of theirsmall size, low equivalent series resistance (ESR) and highRMS current capability. Also, recently, designers havebeen looking to ceramic capacitors due to shortages oftantalum capacitors.
上傳時(shí)間： 2013-11-05
上傳用戶：comer1123
This collection of circuits was worked out between June1991 and July of 1994. Most were designed at customerrequest or are derivatives of such efforts. All representsubstantial effort and, as such, are disseminated here forwider study and (hopefully) use.1 The examples areroughly arranged in categories including power conversion,transducer signal conditioning, amplifiers and signalgenerators. As always, reader comment and questionsconcerning variants of the circuits shown may be addresseddirectly to the author.
標(biāo)簽： 測(cè)量 控制 實(shí)用電路 分
上傳時(shí)間： 2013-11-15
上傳用戶：凌云御清風(fēng)
Most portable computers have built-in sockets to acceptsmall PC cards for use as extended memories, fax modems,network interfaces, wireless communicators and awide assortment of other functions. The Personal ComputerMemory Card International Association (PCMCIA)has released specifications that outline the general powerrequirements for these cards.
標(biāo)簽： PCMCIA 卡插槽 電源管理系統(tǒng)
上傳時(shí)間： 2013-11-18
上傳用戶：bcjtao
For a variety of reasons, it is desirable to charge batteriesas rapidly as possible. At the same time, overchargingmust be limited to prolong battery life. Such limitation ofovercharging depends on factors such as the choice ofcharge termination technique and the use of multi-rate/multi-stage charging schemes. The majority of batterycharger ICs available today lock the user into one fixedcharging regimen, with at best a limited number ofcustomization options to suit a variety of application needsor battery types. The LTC®1325 addresses these shortcomingsby providing the user with all the functionalblocks needed to implement a simple but highly flexiblebattery charger (see Figure 1) which not only addressesthe issue of charging batteries but also those of batteryconditioning and capacity monitoring.
上傳時(shí)間： 2013-10-19
上傳用戶：royzhangsz
When a system designer specifies a nonisolated dc/dc powermodule, considering the needed input voltage range isequally as important as considering the required performanceattributes and features. Generally, nonisolated moduleshave either a narrow or a wide input voltage range. Narrowinputmodules typically have a nominal input voltage of3.3, 5, or 12 V. For systems that operate from a tightlyregulated input bus—such as those that do not use batterybackup—a narrow-input module is often adequate sincethe input remains fairly stable.Offering greater flexibility, wide-input modules operatewithin a range of 7 to 36 V, which includes the popular12- or 24-V industrial bus. This enables a single module tobe used for generating multiple voltages. These modulesare ideal for industrial controls, HVAC systems, vehicles,medical instrumentation, and other applications that usea loosely regulated distribution bus. In addition, systemspowered by a rectifier/battery charger with lead-acidbattery backup almost always require wide-input modules.System designers who choose power supplies may wantto take a close look at the latest generation of wide-inputdc/dc modules.
標(biāo)簽： Wide-input modules offer dc
上傳時(shí)間： 2014-12-24
上傳用戶：dragonhaixm
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標(biāo)簽： 數(shù)字電源
上傳時(shí)間： 2013-10-16
上傳用戶：dddddd
KEIL7.0完全破解版、中文補(bǔ)丁 k51v700acc.com Keil C51 V7.00 0FDH的漢字bug補(bǔ)丁，同時(shí)處理A51和C51兩個(gè)文件，把他放到\bin\目錄下執(zhí)行。 this software is update to bin\ for hanzhi use SN = K1RIP-M2192-KO14E 用戶名（FIRST & LAST）= 11RI2Z 這是已經(jīng)通過(guò)了的安裝碼 安裝過(guò)程: 可以選擇評(píng)估安裝，也可以選擇完全安裝.選擇完全安裝后輸入上面系列號(hào)，如果提示插入A盤(pán)時(shí)選擇解壓目錄的/ADDON/c51AddON/目錄即可完成安裝。 解壓目錄帶有minitos for keil C51的項(xiàng)目，可以直接在Keil C51上測(cè)試和學(xué)習(xí)嵌入式操作系統(tǒng)。 minitos for 51版本 可以使用keilc51進(jìn)行調(diào)試, 學(xué)習(xí)嵌入操作系統(tǒng) 無(wú)須硬件支持,可以在keilc51可以直接運(yùn)行 minitos 0226 for keil C51的項(xiàng)目文件在: \MiniTOS51_0226移植_Release_20090204\MiniTOS\KeilC51\project 文件名為minitos51.Uv2
上傳時(shí)間： 2014-12-25
上傳用戶：lalalal
畢業(yè)設(shè)計(jì) USB TO Gigabit LAN 網(wǎng)卡 隨著網(wǎng)絡(luò)技術(shù)飛速發(fā)展，多媒體的應(yīng)用越來(lái)越多，人們對(duì)網(wǎng)絡(luò)的要求也越來(lái)越高，為了適應(yīng)市場(chǎng)的需求，網(wǎng)卡出現(xiàn)了。它以其結(jié)構(gòu)簡(jiǎn)單、成本低廉、兼容性強(qiáng)等諸多的優(yōu)越性得到了廣泛的應(yīng)用。由于網(wǎng)絡(luò)的應(yīng)用越來(lái)越廣泛，網(wǎng)卡的應(yīng)用也越來(lái)越多、功能越來(lái)越強(qiáng)大。開(kāi)始時(shí)由于技術(shù)方面的限制，網(wǎng)卡只有10Mbps的吞吐量，由于網(wǎng)絡(luò)技術(shù)的發(fā)展，100Mbps吞吐量的網(wǎng)卡開(kāi)始在市場(chǎng)上得到廣泛的應(yīng)用。而現(xiàn)在1000Mbps吞吐量的網(wǎng)卡的出現(xiàn)又給網(wǎng)絡(luò)的傳輸帶來(lái)了新的活力。 論文中主要闡述了基于以太網(wǎng)的USB TO Gigabit LAN網(wǎng)卡的設(shè)計(jì)與制作。論文首先對(duì)以太網(wǎng)進(jìn)行了介紹，緊接著講了網(wǎng)卡的基本知識(shí)。隨后又對(duì)USB TO Gigabit LAN網(wǎng)卡的電路設(shè)計(jì)和制作進(jìn)行了詳細(xì)的描述。論文還包括了USB TO Gigabit LAN網(wǎng)卡的調(diào)試等內(nèi)容。
上傳時(shí)間： 2014-12-02
上傳用戶：wab1981
利用單片機(jī)具有的智能程序控制的特點(diǎn)，設(shè)計(jì)了基于STC89C52單片機(jī)的"二極管特性測(cè)試器"，可對(duì)二極管一般特性進(jìn)行快速測(cè)試。通過(guò)穩(wěn)定線性電流源給二極管加載恒定電流，然后由高精度模數(shù)轉(zhuǎn)換器測(cè)試其壓降，以此為基礎(chǔ)可判斷二極管好壞、檢測(cè)二極管極性和測(cè)試二極管伏安特性等，避免了用萬(wàn)用表測(cè)試只能測(cè)得極性而不知其特性這一缺點(diǎn)。可用于電子設(shè)計(jì)制作過(guò)程中對(duì)二極管進(jìn)行快速測(cè)試，以確定被測(cè)二極管是否滿足電路的設(shè)計(jì)要求。 Abstract: By making good use of the intelligent control function of the Micro Controller Unit (MCU)， the diode trait tester was designed based on the STC89C52，which could be used to test the trait of a diode rapidly. By loading constant current to diode through the stable linear current source， and measuring the voltage drop of the diode by high-precision analogue-to-digital converter (ADC)， it can judge whether the diode is good or not， distinguish the polarity of the diode， and test the trait that the diode， which can avoid the fault of using a multimeter can only measure the polarity but not the trait. This device can be used to test the trait of a diode quickly，and to make sure that whether a diode can be used in the electronic design or not.
上傳時(shí)間： 2013-11-13
上傳用戶：assef
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