HT45F12
8-Bit Flash MCU with Op Amps & Comparators
Oscillator
Variousꢀoscillatorꢀoptionsꢀofferꢀtheꢀuserꢀaꢀwideꢀrangeꢀofꢀfunctionsꢀaccordingꢀtoꢀtheirꢀvariousꢀ
applicationꢀrequirements.ꢀTheꢀflexibleꢀfeaturesꢀofꢀtheꢀoscillatorꢀfunctionsꢀensureꢀthatꢀtheꢀbestꢀ
optimisationꢀcanꢀbeꢀachievedꢀinꢀtermsꢀofꢀspeedꢀandꢀpowerꢀsaving.ꢀOscillatorꢀselectionsꢀandꢀoperationꢀ
areꢀselectedꢀthroughꢀregisters.
Oscillator Overview
Inꢀadditionꢀtoꢀbeingꢀtheꢀsourceꢀofꢀtheꢀmainꢀsystemꢀclockꢀtheꢀoscillatorsꢀalsoꢀprovideꢀclockꢀsourcesꢀ
forꢀtheꢀWatchdogꢀTimerꢀandꢀTimeꢀBaseꢀfunctions.ꢀExternalꢀoscillatorsꢀrequiringꢀsomeꢀexternalꢀ
componentsꢀasꢀwellꢀasꢀfullyꢀintegratedꢀinternalꢀoscillators,ꢀrequiringꢀnoꢀexternalꢀcomponents,ꢀ
areꢀprovidedꢀtoꢀformꢀaꢀwideꢀrangeꢀofꢀbothꢀfastꢀandꢀslowꢀsystemꢀoscillators.ꢀAllꢀoscillatorꢀoptionsꢀ
areꢀselectedꢀthroughꢀtheꢀconfigurationꢀoptions.ꢀTheꢀhigherꢀfrequencyꢀoscillatorsꢀprovideꢀhigherꢀ
performanceꢀbutꢀcarryꢀwithꢀitꢀtheꢀdisadvantageꢀofꢀhigherꢀpowerꢀrequirements,ꢀwhileꢀtheꢀoppositeꢀ
isꢀofꢀcourseꢀtrueꢀforꢀtheꢀlowerꢀfrequencyꢀoscillators.ꢀWithꢀtheꢀcapabilityꢀofꢀdynamicallyꢀswitchingꢀ
betweenꢀfastꢀandꢀslowꢀsystemꢀclock,ꢀtheꢀdeviceꢀhasꢀtheꢀflexibilityꢀtoꢀoptimizeꢀtheꢀperformance/
powerꢀratio,ꢀaꢀfeatureꢀespeciallyꢀimportantꢀinꢀpowerꢀsensitiveꢀportableꢀapplications.
Type
Exteꢃnal Cꢃystal
Name
HXT
ERC
EC
Freq.
400kHz~1ꢄMHz
910kHzꢆ ꢄMHzꢆ 4MHz
400kHz~1ꢄMHz
910kHzꢆ ꢄ/4/8MHz
3ꢄkHz
Pins
O�C1/O�Cꢄ
O�C1
O�C1
—
Exteꢃnal RC
Exteꢃnal Clock
Inteꢃnal High �ꢀeed RC
Inteꢃnal Low �ꢀeed RC
HIRC
LIRC
—
Oscillator Types
System Clock Configurations
Thereꢀareꢀfiveꢀmethodsꢀofꢀgeneratingꢀtheꢀsystemꢀclock,ꢀfourꢀhighꢀspeedꢀoscillatorsꢀandꢀoneꢀlowꢀ
speedꢀoscillators.ꢀTheꢀhighꢀspeedꢀoscillatorsꢀareꢀtheꢀexternalꢀcrystal/ceramicꢀoscillator,ꢀexternalꢀRCꢀ
networkꢀoscillator,ꢀexternalꢀclockꢀandꢀtheꢀinternalꢀ910kHz,ꢀ2MHz,ꢀ4MHzꢀorꢀ8MHzꢀRCꢀoscillator.ꢀ
Theꢀoneꢀlowꢀspeedꢀoscillatorsꢀisꢀtheꢀinternalꢀ32kHzꢀRCꢀoscillator.ꢀ
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System Clock Configurations
Rev. 0.00
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�eꢀteꢁꢂeꢃ ꢄꢅꢆ ꢄ01ꢄ
HOLTEK [ HOLTEK SEMICONDUCTOR INC ]
