HT69F240 datasheet(45/172 Pages) HOLTEK

45 / 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

Entering the IDLE1 Mode

ThereisonlyonewayforthedevicetoentertheIDLE1Modeandthatistoexecutethe"HALT"

instructionintheapplicationprogramwiththeIDLENbitinSMODregisterequalto"1"andthe

FSYSONbitinSMOD1registerequalto"1".Whenthisinstructionisexecutedundertheconditions

describedabove,thefollowingwilloccur:

• ThesystemclockandfSUBclockwillbeonandtheapplicationprogramwillstopatthe"HALT"

instruction.

• TheDataMemorycontentsandregisterswillmaintaintheirpresentcondition.

• TheWDTwillbeclearedandresumecountingastheWDTclocksourceisderivedfromthefSUB

clock.

• TheI/Oportswillmaintaintheirpresentconditions.

• Inthestatusregister,thePowerDownflag,PDF,willbesetandtheWatchdogtime-outflag,TO,

willbecleared.

Standby Current Considerations

AsthemainreasonforenteringtheSLEEPorIDLEModeistokeepthecurrentconsumptionofthe

devicetoaslowavalueaspossible,perhapsonlyintheorderofseveralmicro-ampsexceptinthe

IDLE1Mode,thereareotherconsiderationswhichmustalsobetakenintoaccountbythecircuit

designerifthepowerconsumptionistobeminimised.SpecialattentionmustbemadetotheI/Opins

onthedevice.Allhigh-impedanceinputpinsmustbeconnectedtoeitherafixedhighorlowlevelas

anyfloatinginputpinscouldcreateinternaloscillationsandresultinincreasedcurrentconsumption.

Thisalsoappliestodeviceswhichhavedifferentpackagetypes,astheremaybeunbonbedpins.

Thesemusteitherbesetupasoutputsorifsetupasinputsmusthavepull-highresistorsconnected.

Caremustalsobetakenwiththeloads,whichareconnectedtoI/Opins,whicharesetupasoutputs.

Theseshouldbeplacedinaconditioninwhichminimumcurrentisdrawnorconnectedonlyto

externalcircuitsthatdonotdrawcurrent,suchasotherCMOSinputs.Alsonotethatadditional

standbycurrentwillalsoberequirediftheconfigurationoptionshaveenabledtheLXTorLIRC

oscillator.

IntheIDLE1Modethesystemoscillatorison,ifthesystemoscillatorisfromthehighspeedsystem

oscillator,theadditionalstandbycurrentwillalsobeperhapsintheorderofseveralhundredmicro-amps.

HT69F240 Datasheet(PDF) 45 Page - Holtek Semiconductor Inc