XRT8020
650MHZCLOCK&CRYSTALMULTIPLIERWITHLVDSOUTPUTS
NOVEMBER2003REV.1.0.2DESCRIPTION
TheXRT8020isamonolithicanalogphaselockedloopthatprovidesahighfrequencyLVDSclockout-put,usingalowfrequencycrystalorreferenceclock.ItisdesignedforSONET/SDHandotherlowjitterap-plications.ThehighperformanceoftheICprovidesaverylowjitterLVDSclockoutputupto650MHz,whileoperatingat3.3volts.TheXRT8020hasaselectable8x,16xor32xinternalmultiplierforanexternalcrys-talorsignalsource.TheOutputEnablepinprovidesatruedisconnectfortheLVDSoutput.Theverycom-pact(4x4mm)lowinductancepackageisidealforhighfrequencyoperation.APPLICATIONS•GigabitEthernet•SONET/SDH•SPI-4Phase2
•8x,16xor32xClockMultiplierforComputerandTelecommunicationSystems
FIGURE1.BLOCKDIAGRAMOFTHEXRT8020
15-40MHzCrystalXTAL112-20pFFEATURES
•575MHzto675MHzoperatingrange•LowOutputJitter:9psrmstypicalat622MHz•OnChipCrystalOscillatorCircuit•Optimizedfor15to40MHzcrystals•Usesparallelfundamentalmodecrystal•Selectable8x,16xor32xmultiplier•Selectable÷1or÷2LVDSoutput
•LVDSoutputmeetsTIA/EIA644ASpecification(2001)
•3.3V±10%LowpowerCMOS:80mWtypical•-40°Cto+85°Coperatingtemperature•Extremelysmall16-leadQFNpackage
+3.3VAVDDAVDDREXT10kΩOVDDXTAL212-20pFXRT8020VoltageReference&BiasGeneratorOscillatorCircuit&InputBufferVCOCalibrationLogicPhaseDetectorChargePumpLoopFilterVCOSelectable÷1or÷2DividerOUTPLVDSOutputOUTNFeedbackDivider÷8,16or32AGND(Crystal)AGNDAGNDFS1FS0PDOEOGNDExarCorporation48720KatoRoad,FremontCA,94538•(510)668-7000•FAX(510)668-7017•www.exar.com
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XRT8020
650MHZCLOCK&CRYSTALMULTIPLIERWITHLVDSOUTPUTS
REV.1.0.2FIGURE2.XRT8020PINLOCATION-(TOPVIEW)
1615141312341211XRT8020109567ORDERINGINFORMATION
PARTNUMBERXRT8020IL
PACKAGE16-PinQFN
OPERATINGTEMPERATURERANGE
-40°Cto+85°C
2
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XRT8020
650MHZCLOCK&CRYSTALMULTIPLIERWITHLVDSOUTPUTS
REV.1.0.2DESCRIPTION....................................................................................................................1
APPLICATIONS.........................................................................................................................................FEATURES................................................................................................................................................
Figure1.BlockDiagramoftheXRT8020........................................................................................ORDERINGINFORMATION...............................................................................................................Figure2.XRT8020PinLocation-(TopView).................................................................................ABSOLUTEMAXIMUMRATINGS.......................................................................................................................ELECTRICALCHARACTERISTICS.....................................................................................................................
Figure3.LVDSOutputWaveformsandTestCircuits....................................................................1.0Calibration.................................................................................................................................................
TABLE1:FREQUENCYSELECTIONTABLE..............................................................................................TABLE2:POWER-DOWNANDOUTPUTTRI-STATESELECTIONTABLE.......................................................2.0Crystalselection.......................................................................................................................................3.0dataandplots...........................................................................................................................................
Figure4.InputReferencedJitterConnectionDiagram.................................................................Figure5.SimplifiedBlockDiagramoftheXRT8020andPECLReceiver....................................Figure6.LVDSDifferentialOutput..................................................................................................Figure7.PECLDifferentialOutput..................................................................................................Figure8.PECLSingle-EndedOutputs(PositiveandNegativeOutputReferencedtoGround)111223355556667789ORDERINGINFORMATION.............................................................................................10
REVISIONS.................................................................................................................................................11
I
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XRT8020
REV.1.0.2650MHZCLOCK&CRYSTALMULTIPLIERWITHLVDSOUTPUTS
PINDESCRIPTION
PIN12345678910111213141516
NAMEAVDDAGNDXTAL1XTAL2AGNDREXTOEPDFS1FS0AGNDOGNDOUTNOUTPOVDDAVDD
OOIIIIIIOTYPE
DESCRIPTION
3.3V±10%AnalogSupplyforCrystalOscillatorAnalogGroundforCrystalOscillatorCrystalpin1orexternalclockinputCrystalpin2(outputdriveforcrystal)AnalogGround
ExternalBiasResistor(10KΩtoground)
OutputEnable,Activelow(Internal50KΩpull-downtoground)PowerDown,ActiveHigh(Internal50KΩpull-downtoground)Frequencyselect\"1\"(Internal50KΩpull-downtoground)Frequencyselect\"0\"(Internal50KΩpull-uptoVDD)AnalogGround
OutputGroundforLVDSoutputsLVDSnegativeoutputfor50ΩlineLVDSpositiveoutputfor50Ωline
3.3V±10%DigitalSupplyforLVDSOutputbuffer3.3V±10%AnalogSupply
ABSOLUTEMAXIMUMRATINGS
Supplyvoltage
VIN
StorageTemperatureOperatingTemperature
ESDREXT(±1%)
-0.5to6.0V-0.5to6.0V-65°Cto+150°C-40°Cto+85°C>2,000volts
10kΩ
ELECTRICALCHARACTERISTICS
PARAMETER
SupplyVoltageSupplycurrentPowerSaveCurrentInputDigitalHighInputDigitalLowCrystalFrequency
SYMBOLVDDIDDIDDVINHVINL
152.0
0.827
MIN3.0
TYP3.325
MAX3.6306
UNITVmAmAVVMHz
VDD=3.3V
VDD=3.3V,PD=1,OEB=0Pins7,8,9,10Pins7,8,9,10
SeeSection2.0forCrystalSelection
CONDITIONS
3
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XRT8020
650MHZCLOCK&CRYSTALMULTIPLIERWITHLVDSOUTPUTS
PARAMETER
CrystalFrequencyClockInputFrequencyPoweronCalibrationtimeMaxFrequencyOutMaxFrequencyOutRisetimeFallTimeDutycycle
DifferentialOutputSkewOutputLoadingOutputVoltageSwingCommonModeVoltageOutputShortCircuitCurrentCycle-to-CycleJitterCycle-to-CycleJitterAccumulatedJitterAccumulatedJitterInputReferencedJitterInputReferencedJitter
VOUTVCM
2501.0
1.2-5.733121299
FOUTFOUTTRTF
45
10100
4501.4-10
575285
350350
55
SYMBOL
MIN2772
TYP
MAX40855675340
UNITMHzMHzmsMHzMHzpsps%psΩmVVmApspspspspsps
Currentlimittoground,VDDorVptoVnrms,at624MHzrms,at312MHzrms,at624MHzrms,312MHz
rmsat622MHz,SeeFigure4rmsat312MHz,SeeFigure4Magnitudeof(OUTP-OUTN)
CONDITIONS
SeeSection2.0forCrystalSelectionACCoupled(FS0=1,FS1=1)
AfterVDDreaches2.8V
NOTE:Calibrationtime=16,000clockcycles624MHznominalFOUT(SeeTable1)312MHznominalFOUT(SeeTable1)CL=5pF,RL=100Ω,(20%-80%)CL=5pF,RL=100Ω,(20%-80%)LVDSoutputSeeFigure3
REV.1.0.24
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XRT8020
REV.1.0.2650MHZCLOCK&CRYSTALMULTIPLIERWITHLVDSOUTPUTS
FIGURE3.LVDSOUTPUTWAVEFORMSANDTESTCIRCUITS
LDVSLevelsTestCircuitOUTP50ΩVOUT50ΩOUTNVCMCL=5pFOUTNLDVSSwitchingTestCircuitOUTPCL=5pFVOUTRL=100ΩLDVSTransitionTimeWaveformOUTP50%VCM(Differential)tskew50%OUTN80%80%VOUT20%0V0V(Differential)20%TRTFTABLE1:FREQUENCYSELECTIONTABLE
FS0PIN101010
FS1PIN91100
CRYSTALORCLOCK
FREQUENCY78.0MHzClock39.0MHz19.5MHz19.5MHz
INTERNALCAPACITOR
NA12pF20pF20pF
MULTIPLYRATIO
8x16x32x32x
OUTPUTDIVIDE
1112
OUTPUTFREQUENCY624MHz624MHz624MHz312MHz
NOTES:1.UseParallelFundamentalmodecrystal2.FS0hasaninternal50KΩ pull-upresistortoVDD3.FS1hasaninternal50KΩpull-downresistortoGNDTABLE2:POWER-DOWNANDOUTPUTTRI-STATESELECTIONTABLE
PDPIN810
OEPIN7X1
STATUS
Outputstri-statedandchipPowered-downOutputtri-stated
NOTES:1.“X\"=Don'tcare2.PDandOEhaveaninternal50KΩpull-downresis-tortoground.1.0CALIBRATION
5
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XRT8020
650MHZCLOCK&CRYSTALMULTIPLIERWITHLVDSOUTPUTS
REV.1.0.2TheXRT8020synthesizerjitterperformanceisoptimizedbycalibrationofitsVoltageControlledOscillator(VCO)uponinitialpowerapplication.ThispowerONcalibrationprocedureisautomaticandcompletelytrans-parenttotheuser.ItisinitiatedautomaticallyuponfirstapplicationofVDD.Inordertobringthecenterfre-quencyoftheVCOclosetothedesiredoutputfrequency,theVCObiascurrentisadjustedviaacurrentDACatinitialpowerapplication.ThecenterfrequencyofVCOischeckedagainstinputreferencefrequencyandcal-ibratedinternallytothedesiredoutputfrequencyvalue.ThesebiasvoltagetrimbitsarethenheldinlatchesforaslongastheVDDisheldabove2.7V(minimumspecifiedoperationalvalueofVDD).TheusershouldnotefollowingimportantfactsaboutthiscalibrationprocedureforproperoperationoftheXRT8020:
•Forproperoperationofthechipandtoachievelowestjitter,theusershouldfollowlayoutguidelinesasdescribedintheUserGuide.
•AninputcrystalofappropriatefrequencyshouldbeconnectedatXTAL1andXTAL2pinsbeforepowerisappliedtothechip.
•AllVDDpinsshouldbetiedto3.3V±10%simultaneously.
•Thepowersupplyshouldturnonwithoutbouncingbelow2.0Vsmoothlytoitsspecifiedvalueinnomorethan50msec.
•ThecalibrationtakesplaceduringVDDrampupbetween2.6Vto3Vvalues.OncetheVDDreachesandmaintains3.0V,thechipretainsthecalibratedVCObiasvoltagesininternallatchesforproperoperation.•Tochangeawidelydifferentvalueofcrystalorinputreferencefrequency,itisrecommendedtopowerdownthechipbybringingVDDto0Vandrestartingafterthechangeinfrequencyhasoccurred.
2.0CRYSTALSELECTION
ItisrecommendedthataFundamentalModeCrystalbeusedasthetimingreferenceoftheXRT8020.Thefol-lowingparthasbeenqualifiedbyEXAR:CITIZENQuartzCrystals20MHz:HCM49-20.000MABJT40MHz:HCM49-40.000MABJT
3.0DATAANDPLOTS
Allplotswererecordedusingthefollowingparametersandtestsetup:•VDD=3.3V
•2”100ΩDifferentialTransmissionLines(fromLVDSoutputstoreceiverinputs)•FundamentalModeCrystalof20MHz•Vref=1.5V(PECLReceiver)
FIGURE4.INPUTREFERENCEDJITTERCONNECTIONDIAGRAM
OutpXRT8020Outn20.0MhzCrystalTektronixP6330DifferentialProbeChannel1MAX9111ESAChannel2TektronixP6245TDS500/600TektronixTDS74046
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XRT8020
REV.1.0.2650MHZCLOCK&CRYSTALMULTIPLIERWITHLVDSOUTPUTS
FIGURE5.SIMPLIFIEDBLOCKDIAGRAMOFTHEXRT8020ANDPECLRECEIVER
100ohmTransmissionLinesXRT8010/20ClockSynthesizerLVDS-To-PECLReceiverFIGURE6.LVDSDIFFERENTIALOUTPUT
LVDSDifferentialOutputs
Freq640.1MHz
Ampl824.0mV
Ch1200mVM500pS
7
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XRT8020
650MHZCLOCK&CRYSTALMULTIPLIERWITHLVDSOUTPUTSFIGURE7.PECLDIFFERENTIALOUTPUT
REV.1.0.2PECLDifferentialOutputs
Freq640.0MHz
Ampl1.42V
Ch1500mVM500pS
8
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XRT8020
REV.1.0.2650MHZCLOCK&CRYSTALMULTIPLIERWITHLVDSOUTPUTS
FIGURE8.PECLSINGLE-ENDEDOUTPUTS(POSITIVEANDNEGATIVEOUTPUTREFERENCEDTOGROUND)
PECLSingle-EndedOutputs
POSOutput
Freq(1)640.3MHz
Freq(2)639.9MHz
Ampl(1)520.0mVAmpl(2)528.0mV
NEGOutput
Ch1Ch2
200mV200mV
M500pS
9
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XRT8020
650MHZCLOCK&CRYSTALMULTIPLIERWITHLVDSOUTPUTS
REV.1.0.2ORDERINGINFORMATION
PARTNUMBER
PACKAGE16-LeadQFN
OPERATINGTEMPERATURERANGE
-40°Cto+85°C
XRT8020IL
PACKAGEDIMENSIONS
16LEADQUADFLATNOLEAD(4mmx4mm,0.65pitchQFN)Rev.1.01θNote:theactualcenterpadismetallicandthesize(D2)isdevice-dependentw/atypicaltoleranceof0.3mmNote:Thecontroldimensionisinmillimeter.SYMBOLAA1A2DD1D2beLINCHESMIN0.0310.0000.0000.1540.1440.0880.0090.0140°MAX0.0390.0020.0390.1610.1520.1000.0150.03012°MILLIMETERSMINMAX0.800.000.003.903.652.240.230.350°1.000.051.004.103.852.540.380.7512°0.0256BSC0.65BSCθ10
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XRT8020
650MHZCLOCK&CRYSTALMULTIPLIERWITHLVDSOUTPUTS
REV.1.0.2REVISIONS
P1.0.1Accumulatedoutputjitterinelectricalspecschangedfrom25ps@624MHzto20@622MhzandTBDto20ps@312Mhz.Pin9hasinternalapull-downresistorinsteadofpull-up.Table1FS0andFS1bitpatternchanged.
P1.0.2Changedtypicaljitterto6psandchangedpackagetoQFN
P1.0.3Correctedpackagedimensiondimension\"e\"to0.65mmBSC.Updatedelectricaltables.Addedde-scriptivesectionsonCalibration,CrystalSelectionandDataandPlots.
1.0.0FinalRelease.Addedintrinsicjittermeasurementstotheelectricalcharacteristics.1.0.1Changedthepagenumbering.ChangedtheQLPtoQFNintheFeaturesonpage1.1.0.2ChangedthePackageDrawingandDimensions.
NOTICE
EXARCorporationreservestherighttomakechangestotheproductscontainedinthispublicationinordertoimprovedesign,performanceorreliability.EXARCorporationassumesnoresponsibilityfortheuseofanycircuitsdescribedherein,conveysnolicenseunderanypatentorotherright,andmakesnorepresen-tationthatthecircuitsarefreeofpatentinfringement.Chartsandschedulescontainedhereinareonlyforillustrationpurposesandmayvarydependinguponauser’sspecificapplication.Whiletheinformationinthispublicationhasbeencarefullychecked;noresponsibility,however,isassumedforinaccuracies.EXARCorporationdoesnotrecommendtheuseofanyofitsproductsinlifesupportapplicationswherethefailureormalfunctionoftheproductcanreasonablybeexpectedtocausefailureofthelifesupportsys-temortosignificantlyaffectitssafetyoreffectiveness.Productsarenotauthorizedforuseinsuchapplica-tionsunlessEXARCorporationreceives,inwriting,assurancestoitssatisfactionthat:(a)theriskofinjuryordamagehasbeenminimized;(b)theuserassumesallsuchrisks;(c)potentialliabilityofEXARCorpo-rationisadequatelyprotectedunderthecircumstances.Copyright2003EXARCorporationDatasheetNovember2003.
Reproduction,inpartorwhole,withoutthepriorwrittenconsentofEXARCorporationisprohibited.
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