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CustomSiliconSolutions,Inc.
20081Version1.
0,October2008cssCustomSiliconSolutions,Inc.
CSS555(C)MicropowerTimer(EEPROMSerialInterface)OverviewTheCSS555andCSS555CIC'sincludeaninternalmemorytostoreconfigurationandtrimdata.
Thedataisstoredinanon-volatilememory(EEPROM)sothattheinformationisheldevenwhenthedeviceisnotpowered.
Afour-wireserialinterfaceprovidesRead/WriteaccesstotheEEPROM.
Tomaintainthestandardnumberof555pins,fourpinshavesecondaryfunctions.
Thealternatefunctionshavebeendefinedsotheydonotinterferewithnormaltimeroperation.
TheEEPROMincludesaninternalprogramvoltagegeneratorsonoexternalhighvoltagesignalsarerequiredtostorenewdata.
ThememoryaccessmodeisinitiatedbyforcingtheCONTROLpintoGND.
Aftertheaccessmodeisenabled,theTRIGGER,RESETandOUTPUTpinsprovidetheSerialClock,DataInandDataOutfunctionsrespectively.
Theyareusedtoentercommands,selectanaddressandinput/outputdata.
Eachaccesscycleconsistsofaneight-bitcontrolbytefollowedbyeightbitsofinput(oroutput)data.
Adetaileddescriptionofthepinfunctions,commands,bitassignmentsandsignaltimingisprovidedinthefollowingfiguresandtables.
Ablockdiagramoftheinterfacecircuitisshownbelow.
(seeFigure1)TheEEPROMdatacanbeprogrammedeitherbeforeorafterthedeviceisinstalledintothesystem.
Ifprogrammingisdoneafterinstallation,asimpleinterfaceportcanbeaddedtothePCBtoallowaccesstotheserialinterfacepins.
SeveralexamplesareshowninFigures7-9.
BlockDiagramSerialInterfaceCircuitFigure1CustomSiliconSolutionsInc.
17951SkyParkCircle,SuiteFIrvine,CA92614(949)797-9220FAX:(949)797-9225www.
CustomSiliconSolutions.
comControlVoltageReset54Trigger2DIN_EnblOutputDischarge37In0In1OutSel2:1MuxApplicationNoteAN555-144DOUTDataInRegisterEnblDINClkCMDADDCommand&AddressRegisterEnblDINClkCA_EnblCA_EnblDIN_EnblCapacitorTrimEEPROM555ConlyEEOUTCT100pF86Threshold8ConfigurationEEPROMControlEEOUTDOUTDIN3555Timer&DecadeCounterConfigInTimerOutDischgReadEEPROM6TrigControlThreshReset555ConlySerialClockSerialDataInEnableEEAccessVsw~0.
75VClkSequenceControllerResetEEAddReadStoreCA_EnblDIN_EnblCMDADDCSS555ICfromAnalogInputPinsCustomSiliconSolutions,Inc.
20082Version1.
0,October2008CSS555MicropowerTimer(EEPROMSerialInterface)SerialInterfaceDescriptionFourpinshavedualfunctionstoprovideReadandWriteaccesstotheEEPROM.
TheCONTROLpinisusedtoenabletheEEPROMprogrammingmode.
ThevoltageattheCONTROLpin(VCONTROL)isnormallysettoVDDbyaninternalresistivedivider.
IfVCONTROLisheldbelow0.
5V,theprogrammingmodeisenabled.
Whentheprogrammingmodeisactive,threeadditionalpinfunctionsaremodifiedtoprovidethe"SerialClock","SerialDataIn"and"SerialDataOut"functions.
ThespecialpinfunctionsforaccessingtheEEPROMarelistedinTable1.
PinFunctionPinNumberPinNamePrimaryorTimerModeSecondaryorEEPROMProgramMode1VSSGNDGND2TRIGGERStartTimerSerialClock3OUTPUTTimerOutputPulseSerialDataOut4RESETStopTimerSerialDataIn5CONTROLUpperTripLevel(VDD)ProgramEnable6THRESHOLDUpperComparatorInput7DISCHARGECTDischargeFET8VDDPositiveSupplyPositiveSupplyTable1Intheprogrammingmode,theserialclockisprovidedbytheTRIGGERpin.
TheRESETpinbecomes"SerialDataIn"and"SerialDataOut"isprovidedbytheOUTPUTpin.
Inthenormaltimingmode,theTRIGGERinputisconnectedtotheinvertinginputofthelowercomparatoranditsswitchlevelis(VCONTROL).
Intheprogrammingmode,theTRIGGERinputdrivesastandardCMOSdigitalinput.
Itsswitchlevelisapproximately(VDD).
AllaccesscyclesstartbyforcingtheCONTROLpinlowandshiftinginaneight-bitcontrolbyte.
(seeFigures2and3)Thecontrolbytecontainsafour-bitcommandandafour-bitaddress.
ThecommandportionisusedtospecifyeitheraReadorWritecycle.
Theaddressportionselectsthelocationtobeaccessed.
AsummaryoftheinterfacecommandsisprovidedinTable2.
IfaReadcommandisentered,thenexteightclocksshiftthecontentsoftheselectedaddressontotheOUTPUTpin.
(ConfigurationbitassignmentsareshowninTable3.
Capacitortrimbits(CSS555Conly)areenteredLSBtoMSB.
)IfaWritecommandisentered,newdataisloadedduringthenexteightclocksanditisprogrammedintotheEEPROMduringthe9thclockpulse.
TheaccesscycleisterminatedwhentheCONTROLpinisreleased.
(TheinternaldividerwillpullituptoVDDandthenormaltimermodewillbere-established.
)InterfaceCommands(ControlByte)ControlControlByteMSBLSBModeDescriptionPinAddressCommandNormal555Timingmode>1.
0VxxxxxxxxReadEE1ReadConfigurationDataCSS555ConlyTable2ConfigurationBits(DataByte)CounterConfigurationMSBLSBCounterSetting(Multiplier)ModeControlMSBLSBFunctionxxxxx0001(Std.
555)xxxx0xxxAstableMode("Don'tCare"ifStd.
555)xxxxx00110xxxx1xxxMonostableMode("Don'tCare"ifStd.
555)xxxxx010100xxx0xxxxMicroPowerxxxxx0111Kxxx1xxxxLowPowerxxxxx10010Kxx0xxxxxStandardVoltage(Triplevels=&VDD)xxxxx101100Kxx1xxxxxLowVoltage(Triplevels=10%&90%VDD)xxxxx1101MBit6Unusedxxxxx1111(Std.
555)Bit70if555,1if555C(Readonly)Table3AN555-2CustomSiliconSolutions,Inc.
20083Version1.
0,October2008CSS555MicropowerTimer(EEPROMSerialInterface)TimingDiagramsReadEEPROM(1Byte)Figure2ProgramEEPROM(1Byte)Figure3ProgramByte1,Data=2B(hex),ReadByte1Figure4AN555-2Control=12hexDataIn=2BhexEnterData&ProgramByte110ADDCMDXXCounterOutCounterOutPROGENControlPinSCLKTriggerPinDATAINResetPinDATAOUTOutputPinEEREADInternalSignalEESTOREInternalSignalStoreVPP(~20V)InternalSignalStore~10ms00100011110000LoadData&ProgramReadDataLSBLSBDATAINLSB01ADDCMD00100011110000LSBLSBDATAOUTLSBControl=11hexDataOut=2BhexXCounterOutReadByte1XEnterCommand&AddressReadEEDataReadEE(ConfigurationorCapTrimByte)C2C3A0A1A2C1C0A3XXED2ED3ED4ED5ED6ED1ED0ED7CounterOutputCounterOutputPROGENControlPinSCLKTriggerPinDATAINResetPinDATAOUTOutputPinEEADDRInternalBussEEREADInternalSignalEA2EA3EA4EA5EA6EA1EA0EA7XControlByteDataByteEnterCommand&AddressEnterNewEEDataEnterNewEEData&Program1ByteCounterOutputCounterOutputPROGENControlPinSCLKTriggerPinDATAINResetPinDATAOUTOutputPinEEADDRInternalBussEESTOREInternalSignalStoreVPP(~20V)InternalSignalStore~10msC2C3A0A1A2C1C0A3XXED2ED3ED4ED5ED6ED1ED0ED7EA2EA3EA4EA5EA6EA1EA0EA7XControlByteDataByteCustomSiliconSolutions,Inc.
20084Version1.
0,October2008CSS555MicropowerTimer(EEPROMSerialInterface)SerialInterfaceTimingSpecificationsVDD=1.
5Vto5.
5V,Temperature=-40°Cto+85°CParameterSymbolConditionsMinTypMaxUnitsSerialClockPeriodtCLKP50%dutycycle500200nsSerialClockHighTimetCLKHRisingtofallingedge250100nsSerialClockLowTimetCLKLFallingtorisingedge250100nsSerialClockRise/FallTimestR,tF20%to80%,80%to20%100nsDataInSetupTimetDSUDatavalidtorisingclockedge5025nsDataInHoldTimetDHDFallingclockedgetodatainvalid5025nsModeLeadTimetMLDControlpinlowtofirstclockedge1000500nsDataOutputDelayTimetDODRisingclockedgetoDataOutvalid50100nsEEPROMStoreTimetSTRClocklowtime(17thpulse)2510100millisecNote1:Typicalvaluesareforoperationat3V,25°CNote2:DataOutputDelayTime(tDOD)measuredwithCLOAD=10pFandRLOAD=1M.
Table4SerialInterfaceTimingDiagramReadModeFigure5ProgramModeFigure6AN555-2EnterCommand&Address(8clockcycles)ReadEEData(8clockcycles)CMD0tMLDEEMODEControlPinSCLKTriggerPinDATAINResetPinDATAOUTOutputPintDSUtDHDtCLKLtCLKHCMD1tCLKPDOUT0DOUT1DOUT2TimerOutTimerOuttDODExitEEModeEnterCommand,Address&Data(16clockcycles)Store1ByteintoEEPROM(17thclockpulse)CMD0tMLDEEMODEControlPinSCLKTriggerPinDATAINResetPinDATAOUTOutputPintDSUtDHDtCLKLtCLKHCMD1tSTRTimerOutTimerOutExitEEModeCustomSiliconSolutions,Inc.
20085Version1.
0,October2008CSS555CMicropowerTimer(EEPROMSerialInterface)SerialInterfaceExamplesTheCSS555'sserialinterfaceisverystraightforwardandrequiresminimalextracomponentstoimplement.
Itconsistsofthreedigitalinputsignalsthatprovidecontrol,clockanddatainputfunctionsandasingledigitaloutputthatallowsdatatobereadbackfromthedevice.
ThehardwareneededtoprogramtheEEPROMdependsonwhethertheICis"loose"orhasbeeninstalledinasystem.
ExamplesforbothconditionsareshowninFigures7,8and9.
ProgrammingBeforeInstallationThecircuitinFigure7showsadiagramforaninterfaceschematicbetweenanATE(AutomaticTestEquipment)andanuninstalledor"loose"IC.
ThisexampleallowsdatatobewrittentoandreadfromtheinternalEEPROM.
Noexternalcomponentsarerequiredforthisprogrammingsetup.
(ThetimingcomponentsRA,RBandChavebeenomitted.
)Figure7Program&ReadEEPROMOnlyIfthetimerfunctionalsoneedstobetested,thecircuitinFigure8showsaninterfacecircuitthatsupportstheRead,WriteandTimeroperatingmodes.
ThetimingcomponentsRA,RBandChavebeenadded.
TheoutputdriverthatprovidestheVCONTROLsignalhasbeenchangedtoathree-stateoutputbuffer.
ThenormaltimermodeisenabledwhentheVCONTROLbufferisdisabled(OE=0).
ThisallowstheICtosetthevoltagelevelattheCONTROLpin,whichisaboutVDD.
AtimercycleisstartedbypulsingSCLK(Trigger)low.
(Reset/DataInmustbeheldhigh.
)Figure8Program,ReadandTimerFunctionsProgrammingAfterInstallationIftheCSS555hasbeeninstalledintoasystem,thechangesrequiredtoimplementtheserialinterfacearestillrelativelyminor.
AnexampleofoneapproachisshowninFigure9.
TestpointsTP1-TP4havebeenaddedtoprovideaccesstotheTRIGGER,RESET,CONTROLandOUTPUTpins.
Ifthree-statebuffersareusedtogeneratethetestsignals,thedevicecanstillbeoperatedinthetimermode.
Inadditiontothetestport,resistorsR1andR2havebeenaddedtoallowtheexternalATEor"Programmer"tocontroltheTRIGGERandRESETsignals.
SincethesepinsarehighimpedanceCMOSinputs,theadditionalseriesresistancewillnotaffecttheiroperationorincreasetheoperatingcurrentofthecircuit.
Avaluebetween10Kto100KissuggestedforR1andR2.
Figure9ProgramandRead"IntheSystem"+VSCLKDataInDataOutVDDDischgThreshControlCSS555VSSTriggerOutputResetVCONTROLGNDProgramEnableNCNCA.
T.
E.
+VSCLKDataInDataOutVDDDischgThreshControlCSS555VSSTriggerOutputResetVCONTROLGNDProgramEnableA.
T.
E.
RACRBOETrigger+V/ResetTimerOutVDDDischgThreshControlCSS555VSSTriggerOutputResetTestPortSystemPCBRACRBVDDTP1TP2TP3TP4R1R2CustomSiliconSolutions,Inc.
20086Ver.
1.
0–October2008