600TDC-Tkool Electronics

Tkool Electronics

LM3914isamonolithicicthatsensesanalogvoltagelevelsanddrives10LEDs,providingalinearanalogdisplay.Asinglepinchangesthedisplayfromamovingdottoabargraph.ThisisanoverviewofLM3914dot/bardisplaydriver,wewillprovidetheinformationofitspinout,datasheet,parameter,andwherehowtousethisdeviceandsomuchmore.Top5electronicsProjectsusingLM3914-15IC|lm3914lm3915circuitsCatalogLM3914DescriptionLM3914PinoutLM3914FeaturesLM3914ParameterLM3914EquivalentWheretouseLM3914ICHowtouseLM3914ICLM3914CircuitLM3914PackageLM3914ApplicationComponentDatasheetLM3914DescriptionTheLM3914isamonolithicintegratedcircuitthatsensesanalogvoltagelevelsanddrives10LEDs,providingalinearanalogdisplay.Asinglepinchangesthedisplayfromamovingdottoabargraph.CurrentdrivetotheLEDsisregulatedandprogrammable,eliminatingtheneedforresistors.Thisfeatureisonethatallowsoperationofthewholesystemfromlessthan3V.TheLM3914isveryeasytoapplyasananalogmetercircuit.A1.2Vfull-scalemeterrequiresonly1resistorandasingle3Vto15Vsupplyinadditiontothe10displayLEDs.Ifthe1resistorisapot,itbecomestheLEDbrightnesscontrol.Thesimplifiedblockdiagramillustratesthisextremelysimpleexternalcircuitry.Wheninthedotmode,thereisasmallamountofoverlaporfade(about1mV)betweensegments.ThisassuresthatatnotimewillallLEDsbeOFF,andthusanyambiguousdisplayisavoided.Variousnoveldisplaysarepossible.TheLM3914isratedforoperationfrom0Cto+70C.TheLM3914N-1isavailableinan18-leadPDIP(NFK)package.LM3914PinoutLM3914LM3914PinoutPinNumberPinNameDescription1and10to18LED1,LED2,LED3.....LED10The10LEDswhichhastobecontrolledisconnectedtothesepins2V-/GroundGroundpinoftheIC3V+/VccSupplyVoltage(3-18)V4RLOLowlevelvoltageforpotentialdivider5SignalAnalogsignalInputpinbasedonwhichtheLEDiscontrolled.6RHIHighLevelvoltageforpotentialdivider7REFOUTOutputReferenceVoltageforLEDcurrentlimiting8REFADJAdjustpinforvoltagereference9ModeSelectbetweenDot/BarModeLM3914FeaturesAnalogControlledLEDDriverICNumberofcontrollableLEDs:10OperatingVoltage:3Vto18VInputAnalogvoltagerange:1.2Vto12VLEDsinkcurrent:2mAto30mA(programmable)BothDot/BarmodeavailableCanbecascadedtocontrolupto100LEDsAvailablein18-pinDIP,PLCCpackageItcandriveLCDs,LEDsotherwisevacuumfluorescents.Thedototherwisebotdisplaymodecanbeselectedbytheuserexternally.Itcanbeexpandableupto100displays.LM3914ParameterManufacturer:TexasInstrumentsSeries:-Packaging:TubePartStatus:ObsoleteDisplayType:LEDLCDVacuumFluorescent(VF)Configuration:Dot/BarDisplayInterface:-DigitsorCharacters:10StepsCurrent-Supply:6．1mAVoltage-Supply:3V~20VOperatingTemperature:0C~70CMountingType:ThroughHolePackage/Case:18-DIP(0．3007．62mm)SupplierDevicePackage:18-PDIPBasePartNumber:LM3914LM3914EquivalentLM3914EquivalentLEDDriver:LM3916AlternativeLEDDriverICs:CD4511,MAX7219,CD4054WheretouseLM3914ICTheLM3914isananalogcontrolledLEDdriverIC,whichmeansthatitcancontrol(turnonoroff)10LEDlightsusingananaloginputvoltage.Thisintegratedcircuiteliminatestheneedforamicrocontrollerandprogramming,aswellasthehardwarerequiredtocontroltenLEDs.Theanaloginputvoltagecanrangefrom3Vto18V,andtheLEDcurrentcanbecontrolledwithasingleresistoronpin7.(RefOut).TheICalsohastwooperatingmodes:DOTmodeandBARmode,andupto100LEDscanbecontrolledbycascadingmultipleICs.TheseICsarecommonlyusedinvisualalarmsandothermetering/monitoringapplicationsbecausetheLEDscanbecontrolledwithoutflickeringandflawlesslywithequalbrightness.So,ifyourelookingforanICtopoweryourbarLEDlightsoranother10-LEDsequence,thisICmightbeofinteresttoyou.HowtouseLM3914ICThebenefitofusingLM3914isthatitrequireslittlehardwareandissimpletosetup.Simplyconnectthe10LEDstotheIC,setthereferencevoltagesfortheinputvoltage,andlimitthecurrentthroughtheLED,andweredone.ThecircuitbelowisanexampleofanLM3914applicationcircuit.SimplyconnecttheV+andV-topowertheIC,andtheanalogsignalvoltageisconnectedtopin5.Inthiscase,weused9VtopowertheICandmonitorananalogyvoltagerangingfrom0to5V.AlwayskeepinmindthatthevoltageusedtopowertheIC(inthiscase,9V)shouldbeatleast1.5Vhigherthanthemonitoringvoltage(here5V).Becausewearemonitoring0-5Vhere,wesetthelowreferencevoltage(pin4)to0Vandthehighreferencevoltage(pin6)to5V.Asyoumayhavenoticed,weconnectedalltenLEDsdirectlytotheICwithoutusinganycurrentlimitingresistors.ThisisbecausetheIChasaninternalcurrentlimiterandthecurrentvaluecanbesetusingthepinVRO(pin7).Thecurrentcalculationformulasaregivenbelow,whereIisthecurrentflowingthrougheachLEDandRListheresistorconnectedtopin7.I=12.5/RLIntheprecedingexample,weuseda470ohmresistorasRl,sothecurrentthrougheachLEDwillbearound25mA;youcanchangethevalueasneeded.Also,thecathodeoftheLEDisconnectedtotheIC,whiletheanodeisconnectedto+5V.ThisisduetothefactthattheICoutputpinscanonlysinkcurrentandnotsourceit.Theintegratedcircuit(IC)canoperateintwomodes:dotmodeandbarmode.Indotmode,themodepin(pin9)mustbeleftfloating;inthismode,basedontheinputvoltage,onlyoneLEDwillbeturnedon.InBarmode,connectthemodepin(pin9)toV+,andtheLEDwillturnonandoffsequentiallybasedontheinputvoltage.Boththemodesareshowninthegiffileabove.LM3914CircuitThecircuitdiagramforICLM3914isshownbelow.Thecircuitcanbeconstructedusingbothbasicelectricalandelectroniccomponents.TheICLM3914isacriticalcomponentofthiscircuit.AnalarmdrivingswitchforoverrangecanbeconnectedtoabartypeLMseriesLEDdrivingdisplaycircuitinthefollowingcircuit.Thiscircuitissuitableforbardisplays.LM3914BasedAlarmDriverCircuitThecircuithereemploysaPNPtransistor,denotedbyQ1.ThistransistorcanbeconnectedbetweentheLEDpositiveandnegativeterminals,andthebaseterminalofthetransistorisconnectedtotheICspin-10todrivetheLED10.Inseries,analarmunitisconnectedtothetransistorscollectorterminal.Normally,Q1transistor,LED10,andthealarmunitareallturnedoff;however,ifLED10isactivated,itpullsQ1transistorthroughresistorR2andthusactivatesthealarmunit,indicatingthattheconditionisoutofrange.Intheabovecircuit,analarmunitgeneratesanacousticalarmsoundusingapiezosirenunit,otherwiseagatedastableswitchunitthatcontinuouslyactivatestheLEDbrightnessbetweenhighandlowlevelsbeneaththeover-rangestate,oracombinationofboth.Ifdesired,theunitcanbeswitchedtoanyoftheLEDdisplays,andthealarmwillsoundifthatoranyotherhighLEDisenergized.LM3914PackageLM3914ApplicationBatteryMeterforRobotMonitoringof12VCarBatteryTesterCircuitforSoilMoistureMonitoringofLeadAcidBatteryChargerChargeMonitoringCircuitforAtmosphericKitchenExhaustFanforControllingTemperatureMeterCircuitforTemperatureDigitalgaugesElectronicdisplaysLow-costmonitordevicesCrudeBatterylevelindicatorsFadebarsComponentDatasheetLM3914Datasheet