HT45R4U datasheet(79/105 Pages) HOLTEK

79 / 105 page

Rev. 1.10

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Rev. 1.10

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HT45R4U

TinyPowerTM A/D Type

e-Banking ASSP OTP MCU with LCD

Fast Wake-up

TominimisepowerconsumptionthedevicecanentertheSLEEPorIDLE0Mode,wherethesystem

clocksourcetothedevicewillbestopped.Howeverwhenthedeviceiswokenupagain,itcantake

aconsiderabletimefortheoriginalsystemoscillatortorestart,stabiliseandallownormaloperation

toresume.ToensurethedeviceisupandrunningasfastaspossibleaFastWake-upfunctionis

provided,whichallowsfSUB,namelytheLXToscillator,toactasatemporaryclocktofirstdrive

thesystemuntiltheoriginalsystemoscillatorhasstabilised.AstheclocksourcefortheFastWake-

upfunctionisfSUB,theFastWake-upfunctionisonlyavailableintheSLEEP1andIDLE0modes.

WhenthedeviceiswokenupfromtheSLEEP0mode,theFastWake-upfunctionhasnoeffect

becausethefSUBclockisstopped.TheFastWake-upenable/disablefunctioniscontrolledusingthe

FSTENbitintheSMODregister.

IftheHXToscillatorisselectedastheNORMALModesystemclock,andiftheFastWake-up

functionisenabled,thenitwilltakeonetotwotSUBclockcyclesoftheLXToscillatorforthesystem

towake-up.ThesystemwilltheninitiallyrununderthefSUBclocksourceuntil1024HXTclock

cycleshaveelapsed,atwhichpointtheHTOflagwillswitchhighandthesystemwillswitchoverto

operatingfromtheHXToscillator.

IftheHIRCoscillatorisusedasthesystemoscillatorthenitwilltake15~16clockcyclesofthe

HIRCtowakeupthesystemfromtheSLEEPorIDLE0Mode.TheFastWake-upbit,FSTENwill

havenoeffectinthiscase.

System

Oscillator

FSTEN

Bit

Wake-up Time

(SLEEP0 Mode)

Wake-up Time

(SLEEP1 Mode)

Wake-up Time

(IDLE0 Mode)

Wake-up Time

(IDLE1 Mode)

HXT

10�4 HXT �y�les

1~� HXT �y�les

10�4 HXT �y�les

1~� fSUB �y�les (System �uns wit� fSUB

first for 1024 HXT cycles and then

swit��es ove� to �un wit� t�e HXT �lo�k )

1~� HXT �y�les

HIRC

1�~16 HIRC �y�les 1�~16 HIRC �y�les

1~� HIRC �y�les

LXT

10�4 LXT �y�les

1~� LXT �y�les

Wake-up Times

NotethatiftheWatchdogTimerisdisabled,whichmeansthatthefSUBclockderivedfromtheLXT

isoff,thentherewillbenoFastWake-upfunctionavailablewhenthedevicewakesupfromthe

SLEEP0Mode.

Operating Mode Switching

Thedevicecanswitchbetweenoperatingmodesdynamicallyallowingtheusertoselectthebest

performance/powerratioforthepresenttaskinhand.Inthiswaymicrocontrolleroperationsthat

donotrequirehighperformancecanbeexecutedusingslowerclocksthusrequiringlessoperating

currentandprolongingbatterylifeinportableapplications.

Insimpleterms,ModeSwitchingbetweentheNORMALModeandSLOWModeisexecuted

usingtheHLCLKbitandCKS2~CKS0bitsintheSMODregisterwhileModeSwitchingfromthe

NORMAL/SLOWModestotheSLEEP/IDLEModesisexecutedviatheHALTinstruction.When

aHALTinstructionisexecuted,whetherthedeviceenterstheIDLEModeortheSLEEPModeis

determinedbytheconditionoftheIDLENbitintheSMODregisterandFSYSONintheSMOD1

WhentheHLCLKbitswitchestoalowlevel,whichimpliesthatclocksourceisswitchedfromthe

highspeedclocksource,fH,totheclocksource,fH/2~fH/64orfSUB.IftheclockisfromthefSUB,the

highspeedclocksourcewillstoprunningtoconservepower.Theaccompanyingflowchartshows

whathappenswhenthedevicemovesbetweenthevariousoperatingmodes.

HT45R4U Datasheet(PDF) 79 Page - Holtek Semiconductor Inc

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