HT45F56 datasheet(28/90 Pages) HOLTEK

28 / 90 page

Rev. 1.11

April 11, 2017

Rev. 1.11

April 11, 2017

HT45F56

Shock Detector Flash MCU

HT45F56

Shock Detector Flash MCU

Oscillator

Variousoscillatortypesoffertheuserawiderangeoffunctionsaccordingtotheirvariousapplication

requirements.Theflexiblefeaturesoftheoscillatorfunctionsensurethatthebestoptimisationcan

beachievedintermsofspeedandpowersaving.Oscillatorselectionsandoperationareselected

throughacombinationofapplicationprogramandrelevantcontrolregisters.

Oscillator Overview

Inadditiontobeingthesourceofthemainsystemclocktheoscillatorsalsoprovideclocksources

fortheWatchdogTimerandTimeBaseInterrupts.Externaloscillatorsrequiringsomeexternal

componentsaswellasfullyintegratedinternaloscillators,requiringnoexternalcomponents,are

providedtoformawiderangeofbothfastandslowsystemoscillators.Thehigherfrequency

oscillatorprovideshigherperformancebutcarrieswithitthedisadvantageofhigherpower

requirements,whiletheoppositeisofcoursetrueforthelowerfrequencyoscillator.Withthe

capabilityofdynamicallyswitchingbetweenfastandslowsystemclock,thedevicehasthe

flexibilitytooptimizetheperformance/powerratio,afeatureespeciallyimportantinpowersensitive

portableapplications.

Type

Name

Frequency

Internal High Speed RC

HIRC

8 MHz

Internal Low Speed RC

LIRC

32 kHz

Oscillator Types

System Clock Configurations

Therearetwomethodsofgeneratingthesystemclock,onehighspeedoscillatorandonelowspeed

oscillator.Thehighspeedoscillatoristheinternal8MHzRCoscillator,HIRC.Thelowspeed

oscillatoristheinternal32kHzRCoscillator,LIRC.Selectingwhethertheloworhighspeed

oscillatorisusedasthesystemoscillatorisimplementedusingtheHLCLKandCKS2~CKS0bits

intheSMODregisterandasthesystemclockcanbedynamicallyselected.Notethattwooscillator

selectionsmustbemadenamelyonehighspeedandonelowspeedsystemoscillators.Itisnot

possibletochooseano-oscillatorselectionforeitherthehighorlowspeedoscillator.

Prescaler

High Speed

Oscillation

Low Speed

Oscillation

fH/2

fH/16

fH/64

fH/8

fH/4

fH/32

HLCLK,

CKS2~CKS0

fSYS

fSUB

LIRC

fLIRC

HIRC

System Clock Configurations

HT45F56 Datasheet(PDF) 28 Page - Holtek Semiconductor Inc

HT45F56 Datasheet(HTML) 28 Page - Holtek Semiconductor Inc

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