Abstract: Some types of loads require more current during startup than when running. Other loads can be limited to a lower-powercurrent during startup but require a higher operating current. This article describes an application circuit that automatically adjusts apower circuit’s overcurrent protection level up or down after startup is complete.
上传时间： 2013-10-23
上传用户：swaylong
高的工作电压高达100V N双N沟道MOSFET同步驱动 The D810DCDC is a synchronous step-down switching regulator controller that can directly step-down voltages from up to 100V, making it ideal for telecom and automotive applications. The D810DCDC uses a constant on-time valley current control architecture to deliver very low duty cycles with accurate cycle-by-cycle current limit, without requiring a sense resistor. A precise internal reference provides 0.5% DC accuracy. A high bandwidth (25MHz) error amplifi er provides very fast line and load transient response. Large 1Ω gate drivers allow the D810DCDC to drive multiple MOSFETs for higher current applications. The operating frequency is selected by an external resistor and is compensated for variations in VIN and can also be synchronized to an external clock for switching-noise sensitive applications. Integrated bias control generates gate drive power from the input supply during start-up and when an output shortcircuit occurs, with the addition of a small external SOT23 MOSFET. When in regulation, power is derived from the output for higher effi ciency.
上传时间： 2013-10-24
上传用户：wd450412225
Although recent popular attention is focused on LithiumIon batteries, one must not forget that other batterychemistries, such as Nickel Cadmium (NiCd) and NickelMetal Hydride (NiMH) have advantages in rechargeablepower systems. Nickel-based batteries are robust, capableof high discharge rates, have good cycle life, do notrequire special protection circuitry and are less expensivethan Li-Ion. Among the two, NiMH batteries are rapidlyreplacing NiCd because of their higher capacity (40% to50% more) and the environmental concerns of the toxiccadmium contained in NiCd batteries.
上传时间： 2013-11-04
上传用户：qq10538412
While simplicity and high effi ciency (for cool running) areno longer optional features in isolated power supplies, itis traditionally diffi cult to achieve both. Achieving higheffi ciency often requires the use of advanced topologiesand home-brewed secondary synchronous rectifi cationschemes once reserved only for higher power applications.This only adds to the parts count and to the designcomplexity associated with the reference and optocouplercircuits typically used to maintain isolation. Fortunately, abreakthrough IC makes it possible to achieve both high efficiency and simplicity in a synchronous fl yback topology.The LT®3825 simplifi es and improves the performance oflow voltage, high current fl yback supplies by providingprecise synchronous rectifi er timing and eliminating theneed for optocoupler feedback while maintaining excellentregulation and superior loop response.
上传时间： 2013-10-16
上传用户：wayne595
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.
上传时间： 2014-12-24
上传用户：jasson5678
现有基于MAX7219芯片的数码管驱动电路只适用于小尺寸LED，为扩展其使用范围，在介绍动态显示芯片MAX7219功能的基础上，提出了一个基于该芯片的8位高亮度8英寸数码管驱动电路。电路保留了MAX7219芯片的功能强大、编程简单等优点，通过74LS273锁存器和ULN2803达林顿驱动器，实现了对任意大尺寸数码管提供较高电压和电流驱动的静态显示，并亮度可调。 Abstract: The existing display-driving circuit based on MAX7219 was only applicable to small-size LED. To expand its use, based on the function introduction of dynamic display chip MAX7219, a display-driving circuit for high-brightness 8-bit LED with the size of 8-inch was proposed. The advantages of MAX7219 were retained, such as powerful function and simple programming. Static display with adjustable brightness for large-size LED with higher voltage and current was achieved with the help of 74LS273 and ULN2803.
上传时间： 2013-10-23
上传用户：31633073
生活中许多目标的高度和水平距离需要进行测量。目前主要的测量方法，仍以传统的皮尺丈量为主，测量效率不高，有时还很不方便，没有技术成熟的数字式测高测距产品。以基本的数学方法为理论依据，利用遥控小车做为载体，采用角度传感器测量角度、霍尔传感器测量水平距离等，通过单片机LM3S615进行数据计算，实现了对待测目标物体的高度、水平距离等数据的快速、精确和数字式的测量，高度测量精度可达99.06%，水平测量精度则可达98.06%。 Abstract: In our lives， the height and horizontal distance of some goals are needed to be measured. Because the currently used methods are still traditional tape-based measuring methods， and the measuring efficiency is low and inconvenient so some kinds of digital and portable measuring methods or instruments are needed. Based on the basic math theory， this paper designed and manufactured a portable， digital and remote controlled measuring mobile small vehicle， which assembled with angle measuring sensor for angle measurement and Hall sensor for horizontal distance measuring. MCU LM3S615 calculated the height and horizontal distance data gotten from these sensors. The measuring process is simple， the measuring results are more accurate and the measuring efficiency is higher than traditional measure instruments. The accuracy of height and distance measurement can reach 99.06% and 98.06%.
上传时间： 2013-10-30
上传用户：jackandlee
实时时钟是微机保护装置的重要部件，在讨论PCF8583结构与功能的基础上，提出采用dsPIC33F系列微处理器与串行I2C时钟PCF8583的接口设计方案，给出了相应的接口电路与软件流程。该设计方案结构简单，可靠性高，开发周期短，具有一定的实用与参考价值。所设计的微机保护装置已投入现场运行，效果良好。 Abstract: Real-time clock chip is an important part in microcomputer protection device.Based on discussing the structure and function of PCF8583，a new interface scheme which uses dsPIC33F microprocessor and serial clock chip（I2C）PCF8583is proposed.The method of the circuit design and the main software flow are introduced in this paper.The scheme has simple structure，higher reliability and shorter exploitation cycle，so has definite practicality or reference value.The microcomputer protection device has been put into operation with better effects.
上传时间： 2013-11-18
上传用户：Thuan
The PCA9534 is a 16-pin CMOS device that provide 8 bits of General Purpose parallel Input/Output (GPIO) expansion for I2C-bus/SMBus applications and was developed to enhance the NXP Semiconductors family of I2C-bus I/O expanders. The improvements include higher drive capability, 5 V I/O tolerance, lower supply current, individual I/O configuration, 400 kHz clock frequency, and smaller packaging. I/O expanders provide a simple solution when additional I/O is needed for ACPI power switches, sensors, push buttons, LEDs, fans, etc.
上传时间： 2013-11-17
上传用户：vodssv
The LPC1769/68/67/66/65/64 are ARM Cortex-M3 based microcontrollers for embedded applications featuring a high level of integration and low power consumption. The ARM Cortex-M3 is a next generation core that offers system enhancements such as enhanced debug features and a higher level of support block integration.
上传时间： 2014-02-20
上传用户：13215175592
