LM2907EP/LM2917EPEnhancedPlasticFrequencytoVoltageConverterJune2004
LM2907EP/LM2917EP
EnhancedPlasticFrequencytoVoltageConverter
GeneralDescription
TheLM2907EP,LP2917EPseriesaremonolithicfrequencytovoltageconverterswithahighgainopamp/comparatordesignedtooperatearelay,lamp,orotherloadwhentheinputfrequencyreachesorexceedsaselectedrate.Thetachometerusesachargepumptechniqueandoffersfre-quencydoublingforlowripple,fullinputprotectionintwoversions(LM2907-8EP,LM2917-8EP)anditsoutputswingstogroundforazerofrequencyinput.
Theopamp/comparatorisfullycompatiblewiththetachom-eterandhasafloatingtransistorasitsoutput.Thisfeatureallowseitheragroundorsupplyreferredloadofupto50mA.ThecollectormaybetakenaboveVCCuptoamaximumVCEof28V.
Thetwobasicconfigurationsofferedincludean8-pindevicewithagroundreferencedtachometerinputandaninternalconnectionbetweenthetachometeroutputandtheopampnon-invertinginput.Thisversioniswellsuitedforsinglespeedorfrequencyswitchingorfullybufferedfrequencytovoltageconversionapplications.
Themoreversatileconfigurationsprovidedifferentialta-chometerinputanduncommittedopampinputs.Withthisversionthetachometerinputmaybefloatedandtheopampbecomessuitableforactivefilterconditioningofthetachom-eteroutput.
Bothoftheseconfigurationsareavailablewithanactiveshuntregulatorconnectedacrossthepowerleads.Theregulatorclampsthesupplysuchthatstablefrequencytovoltageandfrequencytocurrentoperationsarepossiblewithanysupplyvoltageandasuitableresistor.ENHANCEDPLASTIC
•ExtendedTemperaturePerformanceof−40˚Cto+85˚C•BaselineControl-SingleFab&AssemblySite
Features
nGroundreferencedtachometerinputinterfacesdirectlywithvariablereluctancemagneticpickups
nOpamp/comparatorhasfloatingtransistoroutputn50mAsinkorsourcetooperaterelays,solenoids,meters,orLEDs
nFrequencydoublingforlowripple
nTachometerhasbuilt-inhysteresiswitheitherdifferentialinputorgroundreferencedinputnBuilt-inzeneronLM2917EPn±0.3%linearitytypical
nGroundreferencedtachometerisfullyprotectedfromdamageduetoswingsaboveVCCandbelowground
Advantages
nnnn
OutputswingstogroundforzerofrequencyinputEasytouse;VOUT=fINxVCCxR1xC1
OnlyoneRCnetworkprovidesfrequencydoublingZenerregulatoronchipallowsaccurateandstable
frequencytovoltageorcurrentconversion(LM2917EP)
Applications
nSelectedMilitaryApplicationsnSelectedAvionicsApplications
••••
ProcessChangeNotification(PCN)Qualification&ReliabilityData
Solder(PbSn)LeadFinishisstandard
EnhancedDiminishingManufacturingSources(DMS)Support
OrderingInformation
PARTNUMBERLM2907MX-8EPLM2917MXEP(Notes1,2)
VINPARTNUMBERV62/04635-01V62/04635-02TBD
NSPACKAGENUMBER(Note3)M08AM14ATBD
Note1:Forthefollowing(EnhancedPlastic)versions,checkforavailablility:LM2907M-8EP,LM2907MEP,LM2907MXEP,LM2907N-8EP,LM2907NEPandLM2917M-8EP,LM2917MX-8EP,LM2917MEP,LM2917N-8EP,LM2917NEP.Partslistedwithan\"X\"areprovidedinTape&Reelandpartswithoutan\"X\"areinRails.
Note2:FORADDITIONALORDERINGANDPRODUCTINFORMATION,PLEASEVISITTHEENHANCEDPLASTICWEBSITEAT:www.national.com/mil
Note3:RefertopackagedetailsunderPhysicalDimensions
©2004NationalSemiconductorCorporationDS200906www.national.com
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LM2907EP/LM2917EPEnhancedPlasticBlockandConnectionDiagrams
Dual-In-LineandSmallOutlinePackages,TopViews
20090601
LM2907-8
SeeNSPackageNumberM08AorN08E
20090602
LM2917-8
SeeNSPackageNumberM08AorN08E
2009060320090604
LM2907
SeeNSPackageNumberM14AorN14ALM2917
SeeNSPackageNumberM14AorN14A
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LM2907EP/LM2917EPEnhancedPlasticAbsoluteMaximumRatings(Note4)
IfMilitary/Aerospacespecifieddevicesarerequired,pleasecontacttheNationalSemiconductorSalesOffice/Distributorsforavailabilityandspecifications.SupplyVoltageCollectorVoltageDifferentialInputVoltageTachometer
OpAmp/ComparatorInputVoltageRangeTachometer
LM2907-8EP,LM2917-8EPLM2907EP,LM2917EP
28V28V28V28V
OpAmp/ComparatorPowerDissipation(Note4)LM2907-8EP,LM2917-8EPLM2907-14EP,LM2917-14EPOperatingTemperatureRangeStorageTemperatureRangeSolderingInformationDual-In-LinePackageSoldering(10seconds)SmallOutlinePackageVaporPhase(60seconds)
0.0Vto+28V
1200mW1580mW−40˚Cto+85˚C−65˚Cto+150˚C
260˚C215˚C220˚C
±28V
0.0Vto+28V
Infrared(15seconds)
ElectricalCharacteristics
SymbolTACHOMETER
InputThresholdsHysteresisOffsetVoltage
LM2907EP/LM2917EPLM2907-8EP/LM2917-8EPInputBiasCurrent
VOHVOLI2,I3I3K
Pin2Pin2
OutputCurrentLeakageCurrentGainConstantLinearity
OP/AMPCOMPARATORVOSIBIASInputCommon-ModeVoltageVoltageGainOutputSinkCurrentOutputSourceCurrentSaturationVoltage
Parameter
VCC=12VDC,TA=25˚C,seetestcircuit
Conditions
VIN=250mVp-p@1kHz(Note5)VIN=250mVp-p@1kHz(Note5)VIN=250mVp-p@1kHz(Note5)
3.55
VIN=±50mVDCVIN=+125mVDC(Note6)VIN=−125mVDC(Note6)V2=V3=6.0V(Note7)I2=0,V3=0(Note6)
fIN=1kHz,5kHz,10kHz(Note8)VIN=6.0VVIN=6.0V
0
200
VC=1.0VE=VCC−2.0ISINK=5mAISINK=20mAISINK=50mA
1.07.5610.5+13.8
615
40
50100.1
0.51.01.5
0.9−1.0
1.00.3350
140
0.18.32.3180
2400.11.1+1.010500VCC−1.5V
%mVnAVV/mVmAmAVVVVΩmV/˚CmA
10151
mVmVµAVVµAµA
Min
Typ
Max
UnitsmVmV
±10±25
30
±40
ZENERREGULATOR
RegulatorVoltageSeriesResistanceTemperatureStabilityTotalSupplyCurrent
RDROP=470Ω
Note4:Foroperationinambienttemperaturesabove25˚C,thedevicemustbederatedbasedona150˚Cmaximumjunctiontemperatureandathermalresistanceof101˚C/WjunctiontoambientforLM2907-8EPandLM2917-8EP,and79˚C/WjunctiontoambientforLM2907-14EPandLM2917-14EP.
Note5:Hysteresisisthesum+VTH−(−VTH),offsetvoltageistheirdifference.Seetestcircuit.
Note6:VOHisequalto3⁄4xVCC−1VBE,VOLisequalto1⁄4xVCC−1VBEthereforeVOH−VOL=VCC/2.Thedifference,VOH−VOL,andthemirrorgain,I2/I3,arethetwofactorsthatcausethetachometergainconstanttovaryfrom1.0.
Note7:BesurewhenchoosingthetimeconstantR1xC1thatR1issuchthatthemaximumanticipatedoutputvoltageatpin3canbereachedwithI3xR1.ThemaximumvalueforR1islimitedbytheoutputresistanceofpin3whichisgreaterthan10MΩtypically.
Note8:NonlinearityisdefinedasthedeviationofVOUT(@pin3)forfIN=5kHzfromastraightlinedefinedbytheVOUT@1kHzandVOUT@10kHz.C1=1000pF,R1=68kandC2=0.22mFd.
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LM2907EP/LM2917EPEnhancedPlasticTestCircuitandWaveform
20090606
TachometerInputThresholdMeasurement
20090607
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LM2907EP/LM2917EPEnhancedPlasticTypicalPerformanceCharacteristics
TotalSupplyCurrent
ZenerVoltagevsTemperature
20090640
20090641
NormalizedTachometerOutputvsTemperatureNormalizedTachometerOutputvsTemperature
20090642
20090643
TachometerCurrentsI2andI3vsSupplyVoltageTachometerCurrentsI2andI3vsTemperature
20090644
20090645
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LM2907EP/LM2917EPEnhancedPlasticTypicalPerformanceCharacteristics
TachometerLinearityvsTemperature
(Continued)
TachometerLinearityvsTemperature
20090646
20090647
TachometerLinearityvsR1
TachometerInputHysteresis
vsTemperature
20090648
20090649
OpAmpOutputTransistor
CharacteristicsOpAmpOutputTransistor
Characteristics
20090650
20090651
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LM2907EP/LM2917EPEnhancedPlasticApplicationsInformation
TheLM2907EPseriesoftachometercircuitsisdesignedforminimumexternalpartcountapplicationsandmaximumver-satility.Inordertofullyexploititsfeaturesandadvantageslet’sexamineitstheoryofoperation.Thefirststageofop-erationisadifferentialamplifierdrivingapositivefeedbackflip-flopcircuit.Theinputthresholdvoltageistheamountofdifferentialinputvoltageatwhichtheoutputofthisstagechangesstate.Twooptions(LM2907-8EP,LM2917-8EP)haveoneinputinternallygroundedsothataninputsignalmustswingaboveandbelowgroundandexceedtheinputthresholdstoproduceanoutput.Thisisofferedspecificallyformagneticvariablereluctancepickupswhichtypicallypro-videasingle-endedacoutput.Thissingleinputisalsofullyprotectedagainstvoltageswingsto±28V,whichareeasilyattainedwiththesetypesofpickups.
Thedifferentialinputoptions(LM2907EP,LM2917EP)givetheusertheoptionofsettinghisowninputswitchinglevelandstillhavethehysteresisaroundthatlevelforexcellentnoiserejectioninanyapplication.Ofcourseinordertoallowtheinputstoattaincommon-modevoltagesaboveground,inputprotectionisremovedandneitherinputshouldbetakenoutsidethelimitsofthesupplyvoltagebeingused.Itisveryimportantthataninputnotgobelowgroundwithoutsomeresistanceinitsleadtolimitthecurrentthatwillthenflowintheepi-substratediode.
Followingtheinputstageisthechargepumpwheretheinputfrequencyisconvertedtoadcvoltage.Todothisrequiresonetimingcapacitor,oneoutputresistor,andanintegratingorfiltercapacitor.Whentheinputstagechangesstate(duetoasuitablezerocrossingordifferentialvoltageontheinput)thetimingcapacitoriseitherchargedordischargedlinearlybetweentwovoltageswhosedifferenceisVCC/2.Theninonehalfcycleoftheinputfrequencyoratimeequalto1/2fINthechangeinchargeonthetimingcapacitorisequaltoVCC/2xC1.Theaverageamountofcurrentpumpedintooroutofthecapacitorthenis:
CHOOSINGR1ANDC1
TherearesomelimitationsonthechoiceofR1andC1whichshouldbeconsideredforoptimumperformance.Thetimingcapacitoralsoprovidesinternalcompensationforthechargepumpandshouldbekeptlargerthan500pFforveryaccu-rateoperation.SmallervaluescancauseanerrorcurrentonR1,especiallyatlowtemperatures.SeveralconsiderationsmustbemetwhenchoosingR1.Theoutputcurrentatpin3isinternallyfixedandthereforeVO/R1mustbelessthanorequaltothisvalue.IfR1istoolarge,itcanbecomeasignificantfractionoftheoutputimpedanceatpin3whichdegradeslinearity.Alsooutputripplevoltagemustbecon-sideredandthesizeofC2isaffectedbyR1.Anexpressionthatdescribestheripplecontentonpin3forasingleR1C2combinationis:
ItappearsR1canbechosenindependentofripple,howeverresponsetime,orthetimeittakesVOUTtostabilizeatanewvoltageincreasesasthesizeofC2increases,soacompro-misebetweenripple,responsetime,andlinearitymustbechosencarefully.
Asafinalconsideration,themaximumattainableinputfre-quencyisdeterminedbyVCC,C1andI2:
TheoutputcircuitmirrorsthiscurrentveryaccuratelyintotheloadresistorR1,connectedtoground,suchthatifthepulsesofcurrentareintegratedwithafiltercapacitor,thenVO=icxR1,andthetotalconversionequationbecomes:
VO=VCCxfINxC1xR1xK
WhereKisthegainconstant—typically1.0.
ThesizeofC2isdependentonlyontheamountofripplevoltageallowableandtherequiredresponsetime.
USINGZENERREGULATEDOPTIONS(LM2917EP)
Forthoseapplicationswhereanoutputvoltageorcurrentmustbeobtainedindependentofsupplyvoltagevariations,theLM2917EPisoffered.Themostimportantconsiderationinchoosingadroppingresistorfromtheunregulatedsupplytothedeviceisthatthetachometerandopampcircuitryalonerequireabout3mAatthevoltagelevelprovidedbythezener.Atlowsupplyvoltagestheremustbesomecurrentflowingintheresistorabovethe3mAcircuitcurrenttooperatetheregulator.Asanexample,iftherawsupplyvariesfrom9Vto16V,aresistanceof470Ωwillminimizethezenervoltagevariationto160mV.Iftheresistancegoesunder400Ωorover600Ωthezenervariationquicklyrisesabove200mVforthesameinputvariation.
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LM2907EP/LM2917EPEnhancedPlasticTypicalApplications
MinimumComponentTachometer
20090608
20090609
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LM2907EP/LM2917EPEnhancedPlasticTypicalApplications
(Continued)
ZenerRegulatedFrequencytoVoltageConverter
20090610
BreakerPointDwellMeter
20090611
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LM2907EP/LM2917EPEnhancedPlasticTypicalApplications
(Continued)
VoltageDrivenMeterIndicatingEngineRPMVO=6V@400Hzor6000ERPM(8CylinderEngine)
20090612
CurrentDrivenMeterIndicatingEngineRPM
IO=10mA@300Hzor6000ERPM(6CylinderEngine)
20090613
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LM2907EP/LM2917EPEnhancedPlasticTypicalApplications
(Continued)
CapacitanceMeter
VOUT=1V–10VforCX=0.01to0.1mFd
(R=111k)
20090614
Two-WireRemoteSpeedSwitch
20090615
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LM2907EP/LM2917EPEnhancedPlasticTypicalApplications
(Continued)
100CycleDelaySwitch
20090616
VariableReluctanceMagneticPickupBufferCircuits
20090639
Precisiontwo-shotoutputfrequencyequalstwiceinputfrequency.
20090617
Pulseheight=VZENER
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LM2907EP/LM2917EPEnhancedPlasticTypicalApplications
FingerTouchorContactSwitch
(Continued)
20090619
20090618
FlashingLEDIndicatesOverspeed
20090620
FlashingbeginswhenfIN≥100Hz.
Flashrateincreaseswithinputfrequencyincreasebeyondtrippoint.
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LM2907EP/LM2917EPEnhancedPlasticTypicalApplications
(Continued)
FrequencytoVoltageConverterwith2PoleButterworthFiltertoReduceRipple
20090621
OverspeedLatch
20090623
20090622
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LM2907EP/LM2917EPEnhancedPlasticTypicalApplications
(Continued)
SomeFrequencySwitchApplicationsMayRequireHysteresisintheComparatorFunctionWhichcanbeImplementedinSeveralWays:
20090624
20090625
20090626
20090627
20090628
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LM2907EP/LM2917EPEnhancedPlasticTypicalApplications
(Continued)
ChangingtheOutputVoltageforanInputFrequencyofZero
20090630
20090629
ChangingTachometerGainCurveorClampingtheMinimumOutputVoltage
20090632
20090631
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LM2907EP/LM2917EPEnhancedPlasticAnti-SkidCircuitFunctions
“Select-Low”Circuit
20090634
VOUTisproportionaltothelowerofthetwoinputwheelspeeds.
20090633
“Select-High”Circuit
20090636
VOUTisproportionaltothehigherofthetwoinputwheelspeeds.
20090635
“Select-Average”Circuit
20090637
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LM2907EP/LM2917EPEnhancedPlasticEquivalentSchematicDiagram
20090638
*ThisconnectionmadeonLM2907-8EPandLM2917-8EPonly.**ThisconnectionmadeonLM2917EPandLM2917-8EPonly.
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LM2907EP/LM2917EPEnhancedPlasticPhysicalDimensions
inches(millimeters)unlessotherwisenoted
8-Lead(0.150\"Wide)MoldedSmallOutlinePackage,JEDEC
NSPackageNumberM08A
14-LeadMoldedSOPackageNSPackageNumberM14A
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LM2907EP/LM2917EPEnhancedPlasticPhysicalDimensions
inches(millimeters)unlessotherwisenoted(Continued)
MoldedDual-In-LinePackage(N)NSPackageNumberN08E
MoldedDual-In-LinePackage(N)NSPackageNumberN14A
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LM2907EP/LM2917EPEnhancedPlasticFrequencytoVoltageConverterNotes
LIFESUPPORTPOLICY
NATIONAL’SPRODUCTSARENOTAUTHORIZEDFORUSEASCRITICALCOMPONENTSINLIFESUPPORTDEVICESORSYSTEMSWITHOUTTHEEXPRESSWRITTENAPPROVALOFTHEPRESIDENTANDGENERALCOUNSELOFNATIONALSEMICONDUCTORCORPORATION.Asusedherein:1.Lifesupportdevicesorsystemsaredevicesorsystemswhich,(a)areintendedforsurgicalimplantintothebody,or(b)supportorsustainlife,andwhosefailuretoperformwhenproperlyusedinaccordancewithinstructionsforuseprovidedinthelabeling,canbereasonablyexpectedtoresultinasignificantinjurytotheuser.BANNEDSUBSTANCECOMPLIANCE
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2.Acriticalcomponentisanycomponentofalifesupportdeviceorsystemwhosefailuretoperformcanbereasonablyexpectedtocausethefailureofthelifesupportdeviceorsystem,ortoaffectitssafetyoreffectiveness.
Nationaldoesnotassumeanyresponsibilityforuseofanycircuitrydescribed,nocircuitpatentlicensesareimpliedandNationalreservestherightatanytimewithoutnoticetochangesaidcircuitryandspecifications.
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