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ChronosGUI
Table1liststhevariousmenuitemsinthisscreen.
Table1.SoftwareSettingsDescription
SectionFunction
VCOSelectSelectsbetweenVCO1andVCO2.OnlyoneVCOcanbeused
duringoperation.SeeCDCE421datasheetforVCOtuningranges.
PrescalarTheprescalarselectionisdeterminedinconjunctionwithVCOand
outputdividerselection.SeetheCDCE421datasheettodetermine
thepropersetting.
OutputDividerTheoutputdividerisdeterminedinconjunctionwiththeVCOand
prescalarsettings.SeetheCDCE421datasheettodeterminethe
propersetting.
DriverSelectSelectsbetweenLVPECLorLVDSoutput.
PECLConfigThisoptionshouldbeactivatedwhenusingLVPECLoutput.When
selected,theUSBcontrollerenablestheonboardLVPECL
termination.
ChargePumpCurrentSelectsappropriatechargepumpcurrent.SeeFigure6andFigure7
forrecommendedconfigurations.
LoopFilterBiasSelectBias0shouldbeusedatalltimes.Bias1isatestmodereservedfor
factoryuse.
LoopFilterSelectstheloopfilterCandRvalues.SeeFigure6andFigure7for
recommendedconfigurations.
VCOCalibrationWhenEnableVCOCalibrationisselected,theCDCE421usesits
internalcalibrationcircuittolockthePLLloop.VCOCalibration
Overrideshouldnotbechecked.TIusesmanualcalibrationfortest
modes.
TITestUseSettingshouldbekeptat0000ibias_100ua.Othersettingsarefor
TIuseonly.
ChronosICConfigSelectUseU13programmingsocketforrapidprogrammingof
Chronos-enableddevices.
SelectUseU8DIE/U9QFNsocketiftheEVMisusinga
direct-mounteddieoraQFN-mounteddevice(typicalconfiguration).
SelectUseU12XTALEVALifusingtheoptional6-pinXOmounting
pads(forChronos-enabledoscillators).
ChronosControlSelectEnablePowertoruntheentireboardfromthehostUSB
voltage.Inthismode,theEVMdoesnotneedanexternal3.3V
powersupply.Ifthisoptionisnotselected,thenanexternal3.3V
supplyandgroundconnectionmustbeattached.
SelectOutputEnabletoprovideaclockoutput.Whennotselected,
theoutputgoestoahigh-Zstate.
PushWriteChronossettingstoRAMtodownloadsettingsintothe
CDCE421on-chipvolatileSRAM.Thesesettingsarelostupon
devicepower-down.
PushWriteChronossettingstoEEPROMNOLOCKINGwhenready
tostoretheconfigurationintheCDCE421nonvolatileEEPROM.The
settingsareavailableafterdevicepower-down.Thesettingscanbe
changedatalatertime.
PushWriteChronossettingstoEEPROMLOCKINGonlyifthe
settingsarepermanentandfinal.Afterthisselection,the
EEPROMislockedandcannotbealteredatalatertime.
USBCommunicationAbrightredlightindicatesthatUSBisnotconnectedornot
communicatingproperly.AgreenlightindicatesthataproperUSB
connectionexists.
10.9MHz–1175MHzLowPhaseNoiseClockEvaluationBoard 12SCAU020–March2007
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