HT45F75 datasheet(42/190 Pages) HOLTEK

42 / 190 page

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HT45F75

Body Fat Scale Flash MCU

HT45F75

Body Fat Scale Flash MCU

Oscillators

Variousoscillatoroptionsoffertheuserawiderangeoffunctionsaccordingtotheirvarious

applicationrequirements.Theflexiblefeaturesoftheoscillatorfunctionsensurethatthebest

optimisationcanbeachievedintermsofspeedandpowersaving.Oscillatorselectionsandoperation

areselectedthroughacombinationofconfigurationoptionsandregisters.

Oscillator Overview

Inadditiontobeingthesourceofthemainsystemclocktheoscillatorsalsoprovideclocksources

fortheWatchdogTimerandTimeBaseInterrupts.Externaloscillatorsrequiringsomeexternal

componentsaswellasfullyintegratedinternaloscillators,requiringnoexternalcomponents,

areprovidedtoformawiderangeofbothfastandslowsystemoscillators.Alloscillatoroptions

areselectedthroughtheconfigurationoptions.Thehigherfrequencyoscillatorsprovidehigher

performancebutcarrywithitthedisadvantageofhigherpowerrequirements,whiletheopposite

isofcoursetrueforthelowerfrequencyoscillators.Withthecapabilityofdynamicallyswitching

betweenfastandslowsystemclock,thedevicehastheflexibilitytooptimizetheperformance/

powerratio,afeatureespeciallyimportantinpowersensitiveportableapplications.

Type

Name

Freq.

Pins

Exte�nal C�ystal

HXT

�00kHz~�0MHz

OSC1/OSC�

Inte�nal High Speed RC

HIRC

�.8� �.8×� o� �.8×3MHz

—

Exte�nal Low Speed C�ystal

LXT

3�.7�8kHz

XT1/XT�

Inte�nal Low Speed RC

LIRC

3�kHz

—

Oscillator Types

System Clock Configurations

Therearefourmethodsofgeneratingthesystemclock,twohighspeedoscillatorsandtwolowspeed

oscillators.Thehighspeedoscillatorsaretheexternalcrystaloscillatorandtheinternal4.8MHz,

4.8×2MHzor4.8×3MHzRCoscillator.Thetwolowspeedoscillatorsaretheinternal32kHzRC

oscillatorandtheexternal32.768kHzcrystaloscillator.Selectingwhethertheloworhighspeed

oscillatorisusedasthesystemoscillatorisimplementedusingtheHLCLKbitandCKS2~CKS0

bitsintheSMODregisterandasthesystemclockcanbedynamicallyselected.

Theactualsourceclockusedforeachofthehighspeedandlowspeedoscillatorsischosen

viaconfigurationoptions.Thefrequencyoftheslowspeedorhighspeedsystemclockisalso

determinedusingtheHLCLKbitandCKS2~CKS0bitsintheSMODregister.Notethattwo

oscillatorselectionsmustbemadenamelyonehighspeedandonelowspeedsystemoscillators.Itis

notpossibletochooseano-oscillatorselectionforeitherthehighorlowspeedoscillator.

HT45F75 Datasheet(PDF) 42 Page - Holtek Semiconductor Inc

HT45F75 Datasheet(HTML) 42 Page - Holtek Semiconductor Inc

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