74LS02 – Quadruple Two Input NOR Gate IC

In the circuit two transistors are connected to form a NOR gate. The two inputs are driven out from bases of two transistors. These two inputs ... Skiptomaincontent Continuetosite>>> 74LS02–QuadrupleTwoInputNORGateIC 5April2018 - 0Comments 74LS02NORGateIC 74LS02Pinout 74LS02isaLOGICGATEICand memberof74XXYYICserieswhicharelogicgates.TherearefourNORgatesintheICandeachgatehastwoinputs,hencethenameQUADRUPLETWOINPUTNORGATE.ThegatesinthechiparedesignedbylowpowerSCHOTTKYTRANSISTORS.   74LS02Pinconfiguration 74LS02isa14PINICasshowninthepinoutdiagram.Thechipisavailableindifferentpackagesandischosendependingonrequirement.Thedescriptionforeachpinisgivenbelow. PinNumber Description NORGATE1 2 1A-INPUT1ofGATE1 3 1B-INPUT2ofGATE1 1 1Y-OUTPUTofGATE1 NORGATE2 5 2A-INPUT1ofGATE2 6 2B-INPUT2ofGATE2 4 2Y-OUTPUTofGATE2 NORGATE3 8 3A-INPUT1ofGATE3 9 3B-INPUT2ofGATE3 10 3Y-OUTPUTofGATE3 NORGATE4 11 4A-INPUT1ofGATE4 12 4B-INPUT2ofGATE4 13 4Y-OUTPUTofGATE4 SHAREDTERMINALS 7 GND-Connectedtoground 14 VCC-Connectedtopositivevoltagetoprovidepowertoallfourgates   FeaturesandSpecifications Operatingvoltagerange:+4.75to+5.25V Maximumsupplyvoltage:7V Maximumcurrentallowedtodrawthrougheachgateoutput:8mA TTLoutputs Lowpowerconsumption MaximumESD:3.5KV TypicalRiseTime:15ns TypicalFallTime:15ns Operatingtemperature:0°C to70°C StorageTemperature:-65°C to150°C   Note:Completetechnicaldetailscanbefoundinthe74LS02Datasheetlinkedatthebottomofthispage.   74LS02Equivalents SN54LS02,IC7402,HCF4077,AnytwotransistorscanbereconfiguredtoformaNORgate.   Wheretouse74LS02IC Therearemanyreasonsforusing74LS02.Hereareafewcaseswhyitisused. 1.Thechipisbasicallyusedwhen(NOR)logicfunctionisrequired.Thechiphasfour(NOR)gatesinit.Wecanuseoneorallgates. 2.Whenyouwantlogicinverter.NORgatesinthischipcanbereconnectedtomakethemNOTgates.EachNORgatecanformasingleNOTgate.Sowecanmake74LS02chipafourNOTgatechipifnecessary. 3.WherehighspeedNORoperationisnecessary.AsmentionedearlierthegatesinthechiparedesignedbySCHOTTKYTRANSISTORS.Withthemtheswitchingdelaysofgatesareminimized.Becauseofthisthechipcanbeusedhighspeedapplications. 4.74LS02isoneofcheapestIC.Itisreallypopularandisavailableeverywhere. 5.ThechipalsoprovidesTTLoutputswhichareamustinsomesystems.   Howtouse74LS02 ThefourNORgatesinthechipmentionedearlierareconnectedinternallyasshownbelow. EachNORgatehereperformsNORoperationfortwologicinputs.AlsotheNORgateisacombinationofORgateandNOTgate. SoNOR=OR+NOT. ThetruthtableofNORgateisgivenas, Input1 Input2 OROutput NOROutput LOW LOW LOW HIGH HIGH LOW HIGH LOW LOW HIGH HIGH LOW HIGH HIGH HIGH LOW   ForrealizingtheabovetruthtableletustakesimplifiedNORgateandhaveitconnectedasshownbelow. InthecircuittwotransistorsareconnectedtoformaNORgate.Thetwoinputsaredrivenoutfrombasesoftwotransistors.Thesetwoinputsareconnectedtobuttons.Outputofthegateistakenoutfromjointcollectorofbothtransistors.ThisoutputisconnectedtoaLEDtroughacurrentlimitingresistor.ThisLEDisconnectedtodetectthestateofoutput.Thebuttonsareconnectedtochangethelogicofinputs.   Nowletusconsiderafewstates: 1. Whenbothbuttonsarenotpressed.Inthatstatethecurrentflowthroughbaseofbothtransistorswillbezero.BecausebasecurrentiszerotransistorsQ1andQ2willbeOFF.SothetotalsupplyvoltageVCCappearsacrossthetransistorsQ1andalsoacrossQ2.BecauseoutputY1isnothingbutvoltageacrosstransistorsQ1orQ2itwillbeHIGH.SowhenINPUTS=LOW,OUTPUT=HIGH. 2.Whenoneofbuttonsispressed.OnlytherelativetransistorwillbeONleavingtheotherOFF.TheONtransistorwillactasshortcircuitanditwilloverlaptheOFFtransistor.Withthatthetotaldropacrossbothtransistorswillbezero.BecausetransistordropiszeroY1willbeLOW.SowhenoneINPUT=HIGH,OUTPUT=LOW. 3.Whenbothbuttonsarepressed.BothtransistorswillbeONandvoltageacrossbothofthemwillbezero.BecausetransistordropiszeroY1willbeLOW.SowhenbothINPUTs=HIGH,OUTPUT=LOW. Afterverifyingthethreestates,youcantellthatwehavesatisfiedtheabovetruthtable.TheoutputequationforNORgatecanbegivenas,Y=A+B. Likethiswecanuseeachgateofthechipdependingonrequirement.   Applications GeneralpurposeNORlogicoperation DigitalElectronics Servers ALUs Memoryunits Networking Digitalsystems   Dimensions (Inches/millimeters) ComponentDatasheet 74LS02NORGateICDatasheet Tags LogicGates RelatedPost Join20K+subscribers Wewillneverspamyou. *indicatesrequired EmailAddress* Name Beapartofourevergrowingcommunity. TPP180andTPI180MedicalandIndustrialAC/DCPowerSupplies TRACOPower's180Wpowersuppliesareofferedinultra-compactopen-frameandenclosedpackages PredictiveMaintenance Reduceunplanneddowntimeandmaximizeyourequipment'slifespanwith24/7predictivemaintenance. IndustrialNet™M12Cat5eandCat6AOvermoldedCordsets Panduit’sM12cordsetsareratedfortenmillionflexcycles,providingdurabilityandreliability. 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