HT69F240 datasheet(36/172 Pages) HOLTEK

36 / 172 page

Rev. 1.20

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Rev. 1.20

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HT69F240

I/O 8-Bit Flash MCU with LED/LCD Driver

HT69F240

I/O 8-Bit Flash MCU with LED/LCD Driver

Operating Modes and System Clocks

Presentdayapplicationsrequirethattheirmicrocontrollershavehighperformancebutoftenstill

demandthattheyconsumeaslittlepoweraspossible,conflictingrequirementsthatareespecially

trueinbatterypoweredportableapplications.Thefastclocksrequiredforhighperformancewill

bytheirnatureincreasecurrentconsumptionandofcoursevice-versa,lowerspeedclocksreduce

currentconsumption.AsHoltekhasprovidedthesedeviceswithbothhighandlowspeedclock

sourcesandthemeanstoswitchbetweenthemdynamically,theusercanoptimisetheoperationof

theirmicrocontrollertoachievethebestperformance/powerratio.

System Clock

ThedevicehasmanydifferentclocksourcesforboththeCPUandperipheralfunctionoperation.

Byprovidingtheuserwithawiderangeofclockoptionsusingconfigurationoptionsandregister

programming,aclocksystemcanbeconfiguredtoobtainmaximumapplicationperformance.

Themainsystemclock,cancomefromeitherahighfrequency,fH,orlowfrequency,fSUB,source,

andisselectedusingtheHLCLKbitandCKS2~CKS0bitsintheSMODregister.Thehighspeed

systemclockcanbesourcedfromanHXTorHIRCoscillator,selectedviaaconfigurationoption.

Thelowspeedsystemclocksourcecanbesourcedfromtheclock,fSUB.IffSUBisselectedthenit

canbesourcedbyeithertheLXTorLIRCoscillators,selectedviaaconfigurationoption.Theother

choice,whichisadividedversionofthehighspeedsystemoscillatorhasarangeoffH/2~fH/64.

ThefSUBclockisusedtoprovideasubstituteclockforthemicrocontrollerjustafterawake-uphas

occurredtoenablefasterwake-uptimes.

HXT

HIRC

Prescaler

LIRC

LXT

HighSpeedOscillation

(HOSC)

LowSpeedOscillation

(LOSC)

fH/2

fH/16

fH/64

fH/8

fH/4

fH/32

HighSpeedOscillation

ConfigurationOption

LowSpeedOscillation

ConfigurationOption

CKS[2:0], HLCLK

fSYS

FastWake-upfromSLEEPModeor

IDLEModeControl(forHXTonly)

fSYS/4

fSUB

fTB

WDT

TimeBase

TBCK

fSUB

System Clock Configurations

Note:WhenthesystemclocksourcefSYSisswitchedtofSUBfromfH,thehighspeedoscillationwillstopto

conservethepower.ThusthereisnofH~fH/64forperipheralcircuittouse.

HT69F240 Datasheet(PDF) 36 Page - Holtek Semiconductor Inc

HT69F240 Datasheet(HTML) 36 Page - Holtek Semiconductor Inc

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