The voltage range of Linear Technology’s PowerPath® circuitscan be easily extended with just a few components, thusallowing them to meet the needs of virtually all applications.This application note presents solutions for circuits thatmust withstand large negative voltages, a reverse adapterinput for example, and circuits that must withstand largepositive inputs, such as automotive load-dump.
上传时间： 2013-10-21
上传用户：几何公差
In a recent discussion with a system designer, the requirementfor his power supply was to regulate 1.5Vand deliver up to 40A of current to a load that consistedof four FPGAs. This is up to 60W of power that must bedelivered in a small area with the lowest height profi lepossible to allow a steady fl ow of air for cooling. Thepower supply had to be surface mountable and operateat high enough effi ciency to minimize heat dissipation.He also demanded the simplest possible solution so histime could be dedicated to the more complex tasks. Asidefrom precise electrical performance, this solution had toremovethe heat generated during DC to DC conversionquickly so that the circuit and the ICs in the vicinity do notoverheat. Such a solution requires an innovative designto meet these criteria:
上传时间： 2013-11-24
上传用户：defghi010
Avalanche photodiodes (APDs) are widely utilized in laserbased fiberoptic systems to convert optical data intoelectrical form. The APD is usually packaged with a signalconditioning amplifier in a small module. An APD receivermodule and attendant circuitry appears in Figure 1. TheAPD module (figure right) contains the APD and a transimpedance(e.g., current-to-voltage) amplifier. An opticalport permits interfacing fiberoptic cable to the APD’sphotosensitive portion. The module’s compact constructionfacilitates a direct, low loss connection between theAPD and the amplifier, necessary because of the extremelyhigh speed data rates involved
上传时间： 2013-10-25
上传用户：brain kung
Occasionally, we are tasked with designing circuitry for aspecific purpose. The request may have customer originsor it may be an in-house requirement. Alternately, a circuitmay be developed because its possibility is simply tooattractive to ignore1. Over time, these circuits accumulate,encompassing a wide and useful body of proven capabilities.They also represent substantial effort. These considerationsmake publication an almost obligatory propositionand, as such, a group of circuits is presented here. This isnot the first time we have displayed such wares and, giventhe encouraging reader response, it will not be the last2.Eighteen circuits are included in this latest effort, roughlyarranged in the categories given in this publication’s title.They appear at the next paragraph.
上传时间： 2013-11-12
上传用户：012345
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.
上传时间： 2013-11-05
上传用户：comer1123
Telecommunication, satellite links and set-top boxes allrequire tuning a high frequency oscillator. The actualtuning element is a varactor diode, a 2-terminal device thatchanges capacitance as a function of reverse bias voltage.1 The oscillator is part of a frequency synthesizingloop, as detailed in Figure 1. A phase locked loop (PLL)compares a divided down representation of the oscillatorwith a frequency reference. The PLL’s output is levelshifted to provide the high voltage necessary to bias thevaractor, which closes a feedback loop by voltage tuningthe oscillator. This loop forces the voltage controlledoscillator (VCO) to operate at a frequency determined bythe frequency reference and the divider’s division ratio.
上传时间： 2013-12-20
上传用户：ABCDE
A large group of fiber optic lasers are powered by DCcurrent. Laser drive is supplied by a current source withmodulation added further along the signal path. Thecurrent source, although conceptually simple, constitutesan extraordinarily tricky design problem. There are anumber of practical requirements for a fiber optic currentsource and failure to consider them can cause laser and/or optical component destruction.
上传时间： 2013-10-30
上传用户：wanghui2438
As logic systems get larger and more complex, theirsupply current requirements continue to rise. Systemsrequiring 100A are fairly common. A high current powersupply to meet such requirements usually requires parallelingseveral power regulators to alleviate the thermalstress on the individual power components. A powersupply designer is left with the choice of how to drive theseparalleled regulators: brute-force single-phase or smartPolyPhaseTM.
上传时间： 2013-10-08
上传用户：zhqzal1014
Photomultipliers (PMT), avalanche photodiodes (APD),ultrasonic transducers, capacitance microphones, radiationdetectors and similar devices require high voltage,low current bias. Additionally, the high voltage must bepristinely free of noise; well under a millivolt is a commonrequirement with a few hundred microvolts sometimesnecessary. Normally, switching regulator confi gurationscannot achieve this performance level without employingspecial techniques. One aid to achieving low noise is thatload currents rarely exceed 5mA. This freedom permitsoutput fi ltering methods that are usually impractical
上传时间： 2013-10-28
上传用户：lhw888
Notebook and palmtop systems need a multiplicity ofregulated voltages developed from a single battery. Smallsize, light weight, and high efficiency are mandatory forcompetitive solutions in this area. Small increases inefficiency extend battery life, making the final productmuch more usable with no increase in weight. Additionally,high efficiency minimizes the heat sinks needed onthe power regulating components, further reducing systemweight and size.
上传时间： 2013-11-11
上传用户：大三三
