PICmicro™微控制器振荡器设计指南
Designingaclockoscillatorwithoutsomeknowledgeof
thefundamentalprincipalsofacousticresonatorsis
possiblebutfraughtwiththeuncertaintyof"cutandtry"
methods.Whiletheoscillatormaybemadetorunwith
thechosenresonator,itisquitelikelythattheunitwill
beslightlyofftheintendedfrequency,begrosslyoff
frequencybecauseitisoperatingonanunintended
mode,orhaveunacceptabletemperaturecharacteris-
ticsbecausethewrongresonatorwaschosenforthe
application.
Thisapplicationnoteisprimarilyforinformational
purposes.Itisintendedtohelpthedesignerofclock
oscillatorsunderstandtheparametersofcrystal
resonatorsandtheterminologyofthecrystalresonator
industry,bothofwhichtendtobesomewhatmysterious
andarcanetotheuninitiated.Detailsofcrystalcutsand
rotations,forinstance,areofnousetotheoscillator
designer,onlythedesignerofcrystals.Theoscillator
designerstillneedstounderstandandbeableto
predicttheperformanceandtrade-offsassociatedwith
theseparameters.Thisisnotanin-depthorrigorous
treatmentofacousticresonators,butapracticalguide,
whichshouldallowthedesignertogainabasic
understanding,andtohelpinchoosingandspecifying
resonators.AN588PICmicroMicrocontrollerOscillatorDesignGuideDesignChallengesAuthor:KimPeckThePICmicromicrocontrollersofferuniquedesignConsultantchallengesbecausetheyareuniquelyexible.FlexibilityusuallydemandsdifcultdecisionsontheDesigningaclockoscillatorwithoutsomeknowledgeofpartofthedesigner,butoffersotherwiseunattainablethefundamentalprincipalsofacousticresonatorsis
