User`s guide

Rev. 1.10 32 November 14, 2014 Rev. 1.10 33 November 14, 2014
HT66FW2230
Wireless Charger A/D Flash 8-Bit MCU
External Crystal/ Ceramic Oscillator – HXT
TheExternalCrystal/CeramicSystemOscillatorisoneofthehighfrequencyoscillatorchoices,
whichisselectedviaregisters.Formostcrystaloscillatorcongurations,thesimpleconnectionof
acrystalacrossOSC1andOSC2willcreatethenecessaryphaseshiftandfeedbackforoscillation,
withoutrequiringexternalcapacitors.However,forsomecrystaltypesandfrequencies,toensure
oscillation,itmaybenecessarytoaddtwosmallvaluecapacitors,C1andC2.Usingaceramic
resonatorwillusuallyrequiretwosmallvaluecapacitors,C1andC2,tobeconnectedasshownfor
oscillationtooccur.ThevaluesofC1andC2shouldbeselectedinconsultationwiththecrystalor
resonatormanufacturer’sspecication.
Foroscillatorstabilityandtominimisetheeffectsofnoiseandcrosstalk,itisimportanttoensure
thatthecrystalandanyassociatedresistorsandcapacitorsalongwithinterconnectinglinesareall
locatedasclosetotheMCUaspossible.




 
   
   
 



          
       
    
Crystal/Resonator Oscillator – HXT
Internal RC Oscillator – HIRC
TheinternalRCoscillatorisafullyintegratedsystemoscillatorrequiringnoexternalcomponents.
TheinternalRCoscillatorhasafixedfrequencyof20MHz.Devicetrimmingduringthe
manufacturingprocessandtheinclusionofinternalfrequencycompensationcircuitsareusedto
ensurethattheinuenceofthepowersupplyvoltage,temperatureandprocessvariationsonthe
oscillationfrequencyareminimised.Notethatifthisinternalsystemclockisselected,asitrequires
noexternalpinsforitsoperation.
Internal 32kHz Oscillator – LIRC
TheInternal32kHzSystemOscillatoristhelowfrequencyoscillator.Itisafullyintegrated
RCoscillatorwithatypicalfrequencyof32kHzat5V,requiringnoexternalcomponentsforits
implementation.Devicetrimmingduringthemanufacturingprocessandtheinclusionofinternal
frequencycompensationcircuitsareusedtoensurethattheinuenceofthepowersupplyvoltage,
temperatureandprocessvariationsontheoscillationfrequencyareminimised.