A light-emitting diode (LED) is a semiconductor device that emits narrow-spectrum incoherent light when forward-biased.The color of the emitted light depends on the chemical composition of the semiconductor material used, and can benear-ultraviolet, visible or infrared. LEDs are more prevalent today than ever before, replacing traditional incandescent andfluorescent bulbs in many lighting applications. Incandescents use a heated filament, are subject to breakage and burnoutand operate at a luminous efficiency of 2% to 4%. Fluorescents are more efficient, at 7% to 12%, but require highdrive voltage and contain mercury, a toxic substance that may be eventually banned in certain countries. LEDs, However,produce light directly through electroluminescence, operate at low voltage and can deliver over 20% luminous efficiency.
上傳時間： 2013-11-07
上傳用戶：xiaoyuer
Abstract: It may sound trite, but it is definitely true: the smart grid has the potential to completely transform the energyindustry. However, smart meters and grid management alone will not ensure the success of the smart grid. Unliketraditional IT networks, smart grids require consideration of energy measurement and security. To completely optimize thistechnology, smart grid designs must focus on energy measurement and security. This tutorial considers the benefits ofboth energy measurement and security and how they make machine-to-machine networks different from traditional IT.
標(biāo)簽： 電能計量 安全性 智能電網(wǎng)
上傳時間： 2013-10-29
上傳用戶：皇族傳媒
Abstract: Investment in smart meters and smart grid end equipment continues to grow worldwide as countriestry to make their electric delivery systems more efficient. However, as critical as the electric deliveryinfrastructure is, it is normally not secured and thus subject to attack. This article describes the concept oflife-cycle security—the idea that embedded equipment in the smart grid must have security designed into theentire life of the product, even back to the contract manufacturer. We also talk about how life-cycle securityapplies to embedded equipment in the smart grid. Potential threats are discussed, as are potential solutionsto mitigate the risks posed by those threats.
標(biāo)簽： 智能電表 智能電網(wǎng)
上傳時間： 2014-12-24
上傳用戶：熊少鋒
Abstract: With its small size and large load (10W) capability, the MAX13256 H-bridge transformer driver is an attractive solution forcharging supercapacitors (supercaps). However, a large capacitance on the output of the circuit can force the driver into fault modeat startup, due to the high initial charge current. This application note presents a solution that allows users to charge a largecapacitance without going into fault.
標(biāo)簽： H橋變壓器 驅(qū)動器 充電 超級電容器
上傳時間： 2013-10-20
上傳用戶：2728460838
This document presents design techniques and reference circuits that power Virtex™-4 FXRocketIO™ multi-gigabit transceivers (MGTs) operating at data rates below 3.125 Gb/s.When using multiple transceivers, it is sometimes preferred to power them from a switchingpower supply. However, switching power supplies generate noise that affects transceiver
標(biāo)簽： RocketIO Virtex XAPP 946
上傳時間： 2013-11-18
上傳用戶：huang111
Low power standby requirements are typically associatedwith battery-powered systems. Automotive systems,for example, commonly require power supplies tomaintain output voltage regulation even under no-loadconditions—while drawing minimal quiescent current topreserve battery life. Rising energy costs, However, haveextended the need for low current standby operation toline-powered systems, such as small plugged-in appliancesfor home and business.
上傳時間： 2013-11-20
上傳用戶：xinyuzhiqiwuwu
To this day, Power over Ethernet (PoE) continues to gainpopularity in today’s networking world. The 12.95Wdelivered to the Powered Device (PD) input supplied bythe Power Sourcing Equipment (PSE) is a universal supply.Each PD provides its own DC/DC conversion from anominal 48V supply, thus eliminating the need for a correctvoltage wall adapter. However, higher power devicescan not take advantage of standard PoE because of itspower limitations, and must rely on a large wall adapteras their primary supply. The new LTC4268-1 breaks thispower barrier by allowing for power of up to 35W for suchpower-hungry 2-pair PoE applications. The LTC4268-1provides a complete solution by integrating a high powerPD interface control with an isolated fl yback controller.
上傳時間： 2014-12-24
上傳用戶：jasson5678
Analog Inputs and Outputs in an S7 PLC are represented in the PLC as a 16-bit integer. Over the nominal span of the analog input or output, the value of this integer will range between - 27648 and +27648. However, it is easier to use the analog values if they are scaled to the same units and ranges as the process being controlled. This applications tip describes methods for scaling analog values to and from engineering units.
上傳時間： 2013-11-17
上傳用戶：3294322651
The MAX9257/MAX9258 programmable serializer/deserializer (SerDes) devices transfer both video data and control signals over the same twisted-pair cable. However, control data can only be transmitted during the vertical blank time, which is indicated by the control-channel-enabled output (CCEN) signal. The electronic control unit (ECU) firmware designer needs to know how quickly to respond to the CCEN signal before it times out and how to calculate this duration. This application note describes how to calculate the duration of the CCEN for the MAX9257/MAX9258 SerDes chipset. The calculation is based on STO timeout, clock frequency, and UART bit timing. The CCEN duration is programmable and can be closed if not in use.
標(biāo)簽： SerDes MAXX 9257 9258
上傳時間： 2014-01-24
上傳用戶：xingisme
Bootloader是微處理器上電時運行的第一段代碼，它可以通過通信接口實現(xiàn)對微處理器內(nèi)部應(yīng)用程序的更新升級，為網(wǎng)絡(luò)化嵌入式產(chǎn)品的應(yīng)用程序升級帶來極大的便利。由于目前沒有統(tǒng)一嵌入式系統(tǒng)的Bootloader。基于NEC 78K0系列單片機(jī)自編程原理，設(shè)計出一個適用于78K0/Fx2系列單片機(jī)的Bootloader，并能夠通過單片機(jī)串口在線升級應(yīng)用程序。 Abstract: Bootloader is the first piece of code executed after microprocessor startup. It makes the embedded product’s firmware update conveniently through communication interface. However， no unified bootloader is available for all kinds of microprocessor products. Based on the principle of self-programming NEC 78K0s’ series， a useful Bootloader which is suitable for 78K0/Fx2s’ series MCU is designed，the design can update the application through serial ports.
標(biāo)簽： Bootloader MCU 自編程
上傳時間： 2013-10-26
上傳用戶：fang2010
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