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
Many system designers need an easy way to producea negative 3.3V power supply. In systems that alreadyhave a transformer, one option is to swap out the existingtransformer with one that has an additional secondarywinding. The problem with this solution is that manysystems now use transformers that are standard, offthe-shelf components, and most designers want toavoid replacing a standard, qualifi ed transformer with acustom version. An easier alternative is to produce thelow negative voltage rail by stepping down an existingnegative rail. For example, if the system already employsan off-the-shelf transformer with two secondary windingsto produce ±12V, and a –3.3V rail is needed, a negativebuck converter can produce the –3.3V output from the–12V rail.
上傳時間： 2013-10-09
上傳用戶：Jerry_Chow
Linear Technology’s DC/DC step-down μModule®regulators are complete switchmode power supplies in asurface-mount package. They include the DC/DC controller,inductor, power switches and supporting circuitry.These highly integrated regulators also provide an easysolution for applications that require negative outputvoltages. In other words, these products can operate asinverting buck-boost regulators. As a result, the lowestpotential in the circuit is not the standard 0V, but –VOUT,which must be tied to the μModule regulator’s GND. Allsignals are now referred to –VOUT.
上傳時間： 2013-10-22
上傳用戶：ztj182002
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.
上傳時間： 2013-10-19
上傳用戶：royzhangsz
The P89LPC912/913/914 are single-chip microcontrollers in low-cost 14-pin packages, based on a high performance processor architecture that executes instructions in two to four clocks, six times the rate of standard 80C51 devices. Many system level functions have been incorporated into the P89LPC912/913/914 in order to reduce component count, board space, and system cost.
上傳時間： 2013-10-12
上傳用戶：司令部正軍級
目錄： 1. Character Type Functions － 字符類型函數 2. Standard C Input/Output Functions － 標準輸入輸出函數 3. Standard Library Functions － 標準庫和內存分配函數 4. Mathematical Functions － 數學函數 5. String Functions － 字符串函數 6. BCD Conversion Functions － BCD 轉換函數 7. Memory Access Functions － 存儲器訪問函數 8. Delay Functions － 延時函數 9. LCD Functions － LCD函數 10. LCD Functions for displays with 4x40 characters － 4×40 字符型LCD函數 11. LCD Functions for displays connected in 8 bit memory mapped mode －以8 位外部存儲 器模式接口的LCD顯示函數 12. I2C Bus Functions － I2C 總線函數 13. National Semiconductor LM75 Temperature Sensor Functions － LM75 溫度傳感器函數 14. Dallas Semiconductor DS1621 Thermometer/Thermostat Functions － DS1621 溫度計函 數 15. Philips PCF8563 Real Time Clock Functions － PCF8563 實時時鐘函數 16. Philips PCF8583 Real Time Clock Functions － PCF8583 實時時鐘函數 17. Dallas Semiconductor DS1302 Real Time Clock Functions － DS1302 實時時鐘函數 18. Dallas Semiconductor DS1307 Real Time Clock Functions － DS1307 實時時鐘函數 19. 1 Wire Protocol Functions － 單線通訊協議函數 20. Dallas Semiconductor DS1820/DS1822 Temperature Sensors Functions － DS1820/1822 溫度傳感器函數 21. SPI Functions － SPI 函數 22. Power Management Functions － 電源管理函數 23. Gray Code Conversion Functions － 格雷碼轉換函數
上傳時間： 2013-10-22
上傳用戶：歸海惜雪
為解決當前計算機串行通訊接口只有USB，難以滿足舊型號設備或某些單片機要求RS232通訊的問題，設計出兩款RS232/USB電路。采用CH341A與MAX223集成電路芯片構建標準9線RS232/USB通用接口轉換器，無需編程。采用CH341A與PIC16F877A構建單片機與計算機之間的USB通訊電路，軟件遵循RS232通訊協議，硬件進行電平轉換。實際使用表明，這兩款產品與計算機端Windows 操作系統下的串口應用程序完全兼容，且通訊過程中無握手失敗現象。 Abstract: To solve the problem that current computer serial communication only with USB interface can not satisfy with the old type equipments or MCU to communicate with RS232， two kinds of RS232/USB circuit were designed.CH341A and MAX223 integrated circuit chips were used to create a standard 9-line RS232/USB universal interface convertor without programme. CH341A and PIC16F877A chips were adopted to build the USB communication circuit between computers and MCU. The software follows RS232 communication protocol， and the hardware converts electrical levels. Actual practices indicate that the two manufactures are compatible with serial application program of Windows operation system completely，and get avoid of handshake lost.
上傳時間： 2013-11-03
上傳用戶：siying
詳細介紹工控軟件組態王與單片機多機串口通訊的設計原理。分析組態王提供的直接與單片機串口通信方法的優點，給出系統基于RS-485總線傳輸的接口電路原理圖。根據組態王提供的通訊協議和單片機多機串口通訊的原理，給出程序設計流程與思路。 Abstract: In this paper，the design principle of communication between multi-SCM and KingView by serial ports is described in detail.We analysis the advantage of method supplied by KingView,by which KingView can communicate with serial ports of SCM directly，and provide the system’s interface circuit based on the RS-485transmission line.We provide flow diagram of programming and thinking on the basis of communication protocol supplied by KingView and principle of communication among multi-SCM through serial ports.
上傳時間： 2013-12-19
上傳用戶：tecman
介紹一種基于CAN總線的牽引變電站自動化系統通訊規約的設計，CAN通訊規約采用標準幀，報文采用主動發送和發送查詢兩種處理形式。該設計在城市輕軌與地鐵牽引變電站中的應用表明：可實現間隔層和通訊處理層的數據快速、可靠的交換，提高牽引變電站的安全性和穩定性 。 Abstract: This paper firstly presents a kind of design dealing with communicational protocol to the traction substation automation system based on CAN bus,and then comes up with the ideas that all frames of CAN communicational protocol should adopt the standard frame,and that messages be processed by two ways:sending initiatively and sending quiries.Subway and light rail application shows that the use of the CAN bus is possible to exchange data quickly and reliably between the layers of the middle and the communicational processing,hence to improve the safety and stability of traction substations.
上傳時間： 2013-11-07
上傳用戶：bs2005
數字信號處理器dsPIC33F集多通道高精度A/D轉換、多通訊模式、看門狗、CMOS Flash技術等于一體，其內部可完成所有數據操作，實現總線不出芯片技術。將該處理器應用于微機保護裝置，提出基于dsPIC33F微處理器的微機保護裝置的設計方案，給出相應的接口電路與軟件流程。該設計方案結構簡單，性價比及可靠性高，開發周期短，具有一定的實用推廣價值。所研制的微機保護裝置現場運行效果良好。 Abstract: The dsPIC33F microprocessor has a plentiful interior resource which contains multi-channel，high precision A/D converters，multi-communication module，watchdog，CMOS Flash technology，and so on.All data manipulations is accomplished interiorly.What is more，it makes the technology that bus does not go beyond the chip comes into practice.The paper put forwards a design scheme based on dsPIC33F microprocessor.The scheme has the advantages of simple structure，high reliability and shortened exploitation cycle.What is more，it has definite practicality and reference.The microcomputer protection device has been put into operation with excellent effects.
上傳時間： 2013-11-16
上傳用戶：開懷常笑
