HT45F75 datasheet(46/190 Pages) HOLTEK

46 / 190 page

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HT45F75

Body Fat Scale Flash MCU

HT45F75

Body Fat Scale Flash MCU

Supplementary Oscillators

Thelowspeedoscillators,inadditiontoprovidingasystemclocksourcearealsousedtoprovide

aclocksourcetootherdevicefunctions.ThesearetheWatchdogTimer,theTimeBaseInterrupts

functionandtheSIM.

Operating Modes and System Clocks

Presentdayapplicationsrequirethattheirmicrocontrollershavehighperformancebutoftenstill

demandthattheyconsumeaslittlepoweraspossible,conflictingrequirementsthatareespecially

trueinbatterypoweredportableapplications.Thefastclocksrequiredforhighperformancewill

bytheirnatureincreasecurrentconsumptionandofcoursevice-versa,lowerspeedclocksreduce

currentconsumption.AsHoltekhasprovidedthisdevicewithbothhighandlowspeedclock

sourcesandthemeanstoswitchbetweenthemdynamically,theusercanoptimisetheoperationof

theirmicrocontrollertoachievethebestperformance/powerratio.

System Clocks

ThedevicehasmanydifferentclocksourcesforboththeCPUandperipheralfunctionoperation.

Byprovidingtheuserwithawiderangeofclockoptionsusingconfigurationoptionsandregister

programming,aclocksystemcanbeconfiguredtoobtainmaximumapplicationperformance.

Themainsystemclock,cancomefromeitherahighfrequencyfHorlowfrequencyfSUBsource,and

isselectedusingtheHLCLKbitandCKS2~CKS0bitsintheSMODregister.Thehighspeedsystem

clockcanbesourcedfromeitheranHXTorHIRCoscillator,selectedviaaconfigurationoption.

ThelowspeedsystemclocksourcecanbesourcedfrominternalclockfSUB.IffSUBisselectedthenit

canbesourcedbyeithertheLXTorLIRCoscillator,selectedviaaconfigurationoption.Theother

choice,whichisadividedversionofthehighspeedsystemoscillatorhasarangeoffH/2~fH/64.

ThefSUBclockisusedtoprovideasubstituteclockforthemicrocontrollerjustafterawake-uphas

occurredtoenablefasterwake-uptimes.ThefSUBisusedasaclocksourcefortheWatchdogtimer,

theTimeBaseinterrupt,theTMsandtheSIMfunctions.

HT45F75 Datasheet(PDF) 46 Page - Holtek Semiconductor Inc