如何看芯片资料

如何阅读数据手册Prepared for the WIMS outreach program Prepared for the WIMS outreach 5/6/02, D. Grover program 5/6/02, D. Grover In order to use a PIC microcontroller, a flip-flop, a photodetector, or 为了使用PIC微控制器腃触发器腃光电检测器或者其practically any electronic device, you need to consult a datasheet. This is the 它任何电子器件腃您都应该参考数据手册。数据手册是生document that the manufacturer provides telling you 产厂商提供给您包含以下信息的文档腆• the typical device performance * 器件的典型性能• minimum and maximum requirements and characteristics * 最小和最大需求和特性• what you can do to the device without harming it * 在不损坏器件的前提下可用它来做什么• suggested uses and hints * 使用建议和提示 Manufacturers want you, the designer, to have a successful experience with 生产厂商希望您腩设计者腪在使用他们的器件时具有their device. They are trying to be helpful. They don’t always succeed. The 成功的经历。他们试图对您有所帮助腃然而这并不总是成datasheet on the following pages is a relatively good datasheet. It tries to 功的。下面 附带的这份数据手册是相对比较好的数据手concisely tell you everything you need to know about the device, a common 册。它试图简明地告诉您那些您想了解的关于该器件腩 一555 timer chip (the duct-tape of the electronics hobbyist). Most datasheets 个通用的555时基芯片腪的所有东西。大部分集成电路for ICs follow the same general layout. 腩IC†j的数据都按照大体同样的布局。 You don’t have to understand everything in a datasheet. There’s a lot of 您没有必要去理解数据手册中的每个部分。数据手册information that might not be of any use to you. The annotations that follow 中有很多信息或许是对您没有任何用处的。后面的注释试try to point out parts of the datasheet that you should pay particular attention 图指出数据手册中你应该要特别留意的那些部分。to. Where do you find datasheets? Nowadays you can find almost any

datasheet on the internet, often in PDF (Acrobat) form. For example, the LM555 datasheet from National Semiconductor is on their website at www.national.com.

What is the LM555? The LM555 is a timer chip that uses external resistors and capacitors to generate either a single pulse of a certain duration, or a continuous sequence of pulses with a variety of pulse widths possible. Because it is a very general purpose collection of functional blocks such as comparators, a flip-flop, internal voltage divider, high power output stage, and so on, a number of different timing-related functions are possible. Entire books have been written about the 555, though it is often used when another IC would work better. (See for example the CD4538 timer chip.)

LM555是什么呢？LM555是一个时基芯片，使用外部电阻和电容它既可以产生一个固定宽度的单脉冲，也可以产生一个脉冲宽度可变的连续脉冲序列。因为它很通用的集成了如比较器，触发器，内部分压器，输出驱动级等等，所以可以实现很多不同的跟时间相关的功能。全面介绍关于555的书有很多，即便其它的IC可以比它工作得更好，555还是经常被使用。（实例请参看CD4538时基芯片。）总会有一个日期。数据手册变动腃尤其是预备版或者修正版腃核对一下日期。LM555TimerFebruary2000LM555TimerGeneralDescriptionTheLM555isahighlystabledeviceforgeneratingaccuratetimedelaysoroscillation.Additionalterminalsareprovidedfortriggeringorresettingifdesired.Inthetimedelaymodeofoperation,thetimeispreciselycontrolledbyoneexternalre-sistorandcapacitor.Forastableoperationasanoscillator,thefreerunningfrequencyanddutycycleareaccuratelycontrolledwithtwoexternalresistorsandonecapacitor.Thecircuitmaybetriggeredandresetonfallingwaveforms,andtheoutputcircuitcansourceorsinkupto200mAordriveTTLcircuits. 特性（Features）提供常规特性信息-- 确认电气特性所在的条件以及特殊情FeaturesnnnnnnnnnDirectreplacementforSE555/NE555TimingfrommicrosecondsthroughhoursOperatesinbothastableandmonostablemodesAdjustabledutycycleOutputcansourceorsink200mAOutputandsupplyTTLcompatibleTemperaturestabilitybetterthan0.005%per˚CNormallyonandnormallyoffoutputAvailablein8-pinMSOPpackage有时常规描述腩General Description•j会给出一些其它地方没提到的特性或者用法。例如腃在某些操作时您需要将某个引脚拉低。ApplicationsnnnnnnnPrecisiontimingPulsegenerationSequentialtimingTimedelaygenerationPulsewidthmodulationPulsepositionmodulationLinearrampgenerator应用提示通常简捷地告诉您该器件是否在您所需要的领域腃但这个列表非常概要。SchematicDiagramDS007851-1通常叫做等效原理图腃该原理不是该芯片中必须的腃但是该芯片将按照里面的来运作。它能帮助解释在数据手册中未被描述的行为。能把这个电路在面包板上搭出来吗腈除非您知道那些并未给出参数的晶体管的参数。©2000NationalSemiconductorCorporationDS007851www.national.com

LM555ConnectionDiagram确认您所看到的引脚分布对应着正确的封装。在后面您将看到封装类型的图。在这里，所有的封装都具有相同的引脚分布，然而并非所有的情形都是如此的。Dual-In-Line,SmallOutlineandMoldedMiniSmallOutlinePackagesDS007851-3TopViewOrderingInformationPackage8-PinSOIC8-PinMSOP8-PinMDIPPartNumberLM555CMLM555CMXLM555CMMLM555CMMXLM555CNPackageMarkingLM555CMLM555CMZ55Z55LM555CNMediaTransportRails2.5kUnitsTapeandReel1kUnitsTapeandReel3.5kUnitsTapeandReelRailsNSCDrawingM08AMUA08AN08E 在分类信息（ Ordering Information ）下，可以找到带有完整零件编号的该器件的每个变种列表。通常开始的几个字母是行业标准或者厂商标识, 接着的是常规标识（“555”）。后缀通常给出封装类型（贴片安装型或直插型），温度范围（宽范围型，当然也会更贵），速度（快速型，当然也会更贵），以及其它各种如功耗，电压范围等等。数据手册中的其它成分：--相关器件，如它可替换的，可直接替换的，或者可以被其它替换的器件--内部方块图--提供编程或者配置该器件的信息（寄存器等）--与其它器件之间的连接（包括输入/输出特性）www.national.com2

绝对最大等级腩Absolute Maximum Ratings•C也叫做极限参数腪给出什么条件将毁坏芯片腃而不是最大运作限制。LM555AbsoluteMaximumRatings(Note2)IfMilitary/Aerospacespecifieddevicesarerequired,pleasecontacttheNationalSemiconductorSalesOffice/Distributorsforavailabilityandspecifications.SupplyVoltagePowerDissipation(Note3)LM555CM,LM555CNLM555CMMOperatingTemperatureRangesLM555CStorageTemperatureRange+18V1180mW613mW0˚Cto+70˚C−65˚Cto+150˚CSolderingInformationDual-In-LinePackageSoldering(10Seconds)260˚CSmallOutlinePackages(SOICandMSOP)VaporPhase(60Seconds)215˚CInfrared(15Seconds)220˚CSeeAN-450“SurfaceMountingMethodsandTheirEffectonProductReliability”forothermethodsofsolderingsurfacemountdevices.ElectricalCharacteristics(Notes1,2)(TA=25˚C,VCC=+5Vto+15V,unlessothewisespecified)ParameterConditions电器特性有时分成直流DC•i电源腃静态输入/输出特性腪和交流AC或动态腃这些可用来计算。LimitsLM555CMin4.5Typ310Max16615VmAUnits注意--数据手册可能讨论多个部分。SupplyVoltageSupplyCurrentVCC=5V,RL=∞VCC=15V,RL=∞(LowState)(Note4)TimingError,MonostableInitialAccuracyDriftwithTemperatureAccuracyoverTemperatureDriftwithSupplyTimingError,AstableInitialAccuracyDriftwithTemperatureAccuracyoverTemperatureDriftwithSupplyThresholdVoltageTriggerVoltageTriggerCurrentResetVoltageResetCurrentThresholdCurrentControlVoltageLevelPin7LeakageOutputHighPin7Sat(Note7)OutputLowOutputLowVCC=15V,I7=15mAVCC=4.5V,I7=4.5mA18080200mVmV(Note6)VCC=15VVCC=5V92.60.4VCC=15VVCC=5VC=0.1µF,(Note5)3.00.300.66751.670.50.50.10.1103.3310.910.40.25114100%%/VxVCCVVµAVmAµAVnARA=1kto100kΩ,C=0.1µF,(Note5)1501.5%ppm/˚C%按照最小和最大限制来设计腃而不是典型值。这让您了解0.1%/V到它比较可能的行为腃但不是最坏的情况。优良的设计不能依靠典型值。2.25%RA,RB=1kto100kΩ,150ppm/˚C注意工作条件。这里该器件工作在一个特定的温度下。通常腃数据手册下面会给出温度相关参数的图腩与那些依赖电源电压腃速度等的参数一样腪。3www.national.com

LM555ElectricalCharacteristics(Notes1,2)Parameter(Continued)(TA=25˚C,VCC=+5Vto+15V,unlessothewisespecified)ConditionsMinOutputVoltageDrop(Low)VCC=15VISINK=10mAISINK=50mAISINK=100mAISINK=200mAVCC=5VISINK=8mAISINK=5mAOutputVoltageDrop(High)ISOURCE=200mA,VCC=15VISOURCE=100mA,VCC=15VVCC=5VRiseTimeofOutputFallTimeofOutputNote1:Allvoltagesaremeasuredwithrespecttothegroundpin,unlessotherwisespecified.Note2:AbsoluteMaximumRatingsindicatelimitsbeyondwhichdamagetothedevicemayoccur.OperatingRatingsindicateconditionsforwhichthedeviceisfunc-tional,butdonotguaranteespecificperformancelimits.ElectricalCharacteristicsstateDCandACelectricalspecificationsunderparticulartestconditionswhichguar-anteespecificperformancelimits.ThisassumesthatthedeviceiswithintheOperatingRatings.Specificationsarenotguaranteedforparameterswherenolimitisgiven,however,thetypicalvalueisagoodindicationofdeviceperformance.Note3:Foroperatingatelevatedtemperaturesthedevicemustbederatedabove25˚Cbasedona+150˚Cmaximumjunctiontemperatureandathermalresistanceof106˚C/W(DIP),170˚C/W(S0-8),and204˚C/W(MSOP)junctiontoambient.Note4:Supplycurrentwhenoutputhightypically1mAlessatVCC=5V.Note5:TestedatVCC=5VandVCC=15V.Note6:ThiswilldeterminethemaximumvalueofRA+RBfor15Voperation.Themaximumtotal(RA+RB)is20MΩ.Note7:Noprotectionagainstexcessivepin7currentisnecessaryprovidingthepackagedissipationratingwillnotbeexceeded.Note8:RefertoRETS555XdrawingofmilitaryLM555HandLM555Jversionsforspecifications.LimitsLM555CTyp0.10.422.5Max0.250.752.5UnitsVVVVV0.2512.512.752.7513.33.31001000.35VVVVnsns注意2：绝对最大级别（Absolute Maximum Ratings）表示超过将损坏芯片的限制。操作级别（Operating Ratings）表示芯片基本功能的，但不保证特殊性能的限制条件。电气参数（Electrical Characteristics）是在保证特殊性能限制下的特殊测试条件下规定的直流和交流电气规范。这假设器件是在操作级别下。虽然规范并不保证在没有给定限制时的参数，然而典型值依然是衡量器件性能的一项很好的指标。www.national.com4

LM555TypicalPerformanceCharacteristicsMinimuimPulseWidthRequiredforTriggeringSupplyCurrentvs.SupplyVoltageDS007851-4DS007851-19HighOutputVoltagevs.OutputSourceCurrentLowOutputVoltagevs.OutputSinkCurrent图表被用来描述那些不容易放在表格里的特性。通常几个被变化--上文中腃供电电流被测量当输入电压被改变时腃并同时显示了三种温度下的值。注意25C是近似室温腩77F•j的温度。DS007851-20DS007851-21LowOutputVoltagevs.OutputSinkCurrentLowOutputVoltagevs.OutputSinkCurrentDS007851-22DS007851-23数据手册的第6页被省略。5

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ApplicationsInformationMONOSTABLEOPERATION这里是示例电路和使用注意。注意通常有其它的应用信息来源腃例如厂商提供的独立的应用注意。NOTE:Inmonostableoperation,thetriggershouldbedrivenhighbeforetheendoftimingcycle.LM555Inthismodeofoperation,thetimerfunctionsasaone-shot(Figure1).Theexternalcapacitorisinitiallyhelddischargedbyatransistorinsidethetimer.Uponapplicationofanega-tivetriggerpulseoflessthan1/3VCCtopin2,theflip-flopissetwhichbothreleasestheshortcircuitacrossthecapacitoranddrivestheoutputhigh.DS007851-7FIGURE3.TimeDelayASTABLEOPERATIONIfthecircuitisconnectedasshowninFigure4(pins2and6connected)itwilltriggeritselfandfreerunasamultivibrator.TheexternalcapacitorchargesthroughRA+RBanddis-chargesthroughRB.Thusthedutycyclemaybepreciselysetbytheratioofthesetworesistors.DS007851-5FIGURE1.MonostableThevoltageacrossthecapacitorthenincreasesexponen-tiallyforaperiodoft=1.1RAC,attheendofwhichtimethevoltageequals2/3VCC.Thecomparatorthenresetstheflip-flopwhichinturndischargesthecapacitoranddrivestheoutputtoitslowstate.Figure2showsthewaveformsgener-atedinthismodeofoperation.Sincethechargeandthethresholdlevelofthecomparatorarebothdirectlypropor-tionaltosupplyvoltage,thetiminginternalisindependentofsupply.这个波形有助于电路调试。并非所有的数据手册应用示例都写得这么充分腃有时你仅得到一个不完整的原理图。对于更复杂的器件腃例如微控制器腃不同的方面可能被放在不同的部分--例如腃时钟电路在一处腃而复位电路却在另一处。阅读整个部分确保正确的使用器件以及提供了所有需要的元件。DS007851-8FIGURE4.AstableDS007851-6VCC=5VTIME=0.1ms/DIV.RA=9.1kΩC=0.01µFTopTrace:Input5V/Div.MiddleTrace:Output5V/Div.BottomTrace:CapacitorVoltage2V/Div.Inthismodeofoperation,thecapacitorchargesanddis-chargesbetween1/3VCCand2/3VCC.Asinthetriggeredmode,thechargeanddischargetimes,andthereforethefre-quencyareindependentofthesupplyvoltage.FIGURE2.MonostableWaveformsDuringthetimingcyclewhentheoutputishigh,thefurtherapplicationofatriggerpulsewillnoteffectthecircuitsolongasthetriggerinputisreturnedhighatleast10µsbeforetheendofthetiminginterval.Howeverthecircuitcanberesetduringthistimebytheapplicationofanegativepulsetotheresetterminal(pin4).Theoutputwillthenremaininthelowstateuntilatriggerpulseisagainapplied.Whentheresetfunctionisnotinuse,itisrecommendedthatitbeconnectedtoVCCtoavoidanypossibilityoffalsetrig-gering.Figure3isanomographforeasydeterminationofR,Cval-uesforvarioustimedelays.7

8-11页被省略。www.national.com

LM555TimerPhysicalDimensionsinches(millimeters)unlessotherwisenoted(Continued)MoldedDual-In-LinePackage(N)NSPackageNumberN08E封装轮廓图也可以作为引脚编号的一个参考腃如果你对引脚编号有疑问的话。注意塑料双列直插封装腩DIP•j是做原型设计最常用的封装。避免贴片封装腩例如SOIC•CMSOP•CPQFP•j•C然而使用合适的插座腃PLCC封装能够比较容易的被焊接腩但是不要不使用适配器而直接使用在塑料原型板上腪。不同的封装类型腩其它因素例如温度范围腃速度等腪价格相差很大腃因此请仔细确认零件编号。最后腃记住数据手册总可能会有错误的。但就像编程一样腃99%的错误是用户错误。如果您找到您认为是错误的地方腃请确认您的数据手册是最新的腃并且发送一个有礼貌的咨询给适当的技术支持。LIFESUPPORTPOLICYNATIONAL’SPRODUCTSARENOTAUTHORIZEDFORUSEASCRITICALCOMPONENTSINLIFESUPPORTDEVICESORSYSTEMSWITHOUTTHEEXPRESSWRITTENAPPROVALOFTHEPRESIDENTANDGENERALCOUNSELOFNATIONALSEMICONDUCTORCORPORATION.Asusedherein:1.Lifesupportdevicesorsystemsaredevicesorsystemswhich,(a)areintendedforsurgicalimplantintothebody,or(b)supportorsustainlife,andwhosefailuretoperformwhenproperlyusedinaccordancewithinstructionsforuseprovidedinthelabeling,canbereasonablyexpectedtoresultinasignificantinjurytotheuser.NationalSemiconductorCorporationAmericasTel:1-800-272-9959Fax:1-800-737-7018Email:support@nsc.comwww.national.comNationalSemiconductorEuropeFax:+49(0)180-5308586Email:europe.support@nsc.comDeutschTel:+49(0)6995086208EnglishTel:+44(0)8702402171FrançaisTel:+33(0)1419187902.Acriticalcomponentisanycomponentofalifesupportdeviceorsystemwhosefailuretoperformcanbereasonablyexpectedtocausethefailureofthelifesupportdeviceorsystem,ortoaffectitssafetyoreffectiveness.NationalSemiconductorAsiaPacificCustomerResponseGroupTel:65-2544466Fax:65-2504466Email:ap.support@nsc.comNationalSemiconductorJapanLtd.Tel:81-3-5639-7560Fax:81-3-5639-7507Nationaldoesnotassumeanyresponsibilityforuseofanycircuitrydescribed,nocircuitpatentlicensesareimpliedandNationalreservestherightatanytimewithoutnoticetochangesaidcircuitryandspecifications.