HT45F75 datasheet(159/190 Pages) HOLTEK

159 / 190 page

Rev. 1.10

158

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Rev. 1.10

159

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HT45F75

Body Fat Scale Flash MCU

HT45F75

Body Fat Scale Flash MCU

LVD Operation

TheLowVoltageDetectorfunctionoperatesbycomparingthepowersupplyvoltage,VDD,or

LVDINpininputvoltagewithapre-specifiedvoltagelevelstoredintheLVDCregister.Whenthe

powersupplyvoltage,VDD,orLVDINpininputvoltagefallsbelowthispre-determinedvalue,the

LVDObitwillbesethighindicatingalowvoltagecondition.TheLowVoltageDetectorfunctionis

suppliedbyareferencevoltage,whichwillbeautomaticallyenabled.Whenthedeviceispowered

downthelowvoltagedetectorwillremainactiveiftheLVDENbitishigh.AfterenablingtheLow

VoltageDetector,atimedelaytLVDSshouldbeallowedforthecircuitrytostabilisebeforereadingthe

LVDObit.NotealsothatastheVDDorLVDINpininputvoltagemayriseandfallratherslowly,at

thevoltagenearsthatofVLVD,theremaybemultiplebitLVDOtransitions.

V LV D

LV DE N

LV DO

t LV DS

LV DI NT

t LV D

V LV DI N o r V DD

LVD Operation

TheLowVoltageDetectoralsohasitsowninterruptwhichiscontainedwithinoneoftheMulti-

functioninterrupts,providinganalternativemeansoflowvoltagedetection,inadditiontopolling

theLVDObit.TheinterruptwillonlybegeneratedafteradelayoftLVDaftertheLVDObithasbeen

sethighbyalowvoltagecondition.WhenthedeviceispowereddowntheLowVoltageDetector

willremainactiveiftheLVDENbitishigh.Inthiscase,theLVFinterruptrequestflagwillbeset,

causinganinterrupttobegeneratedifVDDorLVDINpininputvoltagefallsbelowthepresetLVD

voltage.Thiswillcausethedevicetowake-upfromtheSLEEPorIDLEMode,howeveriftheLow

VoltageDetectorwakeupfunctionisnotrequiredthentheLVFflagshouldbefirstsethighbefore

thedeviceenterstheSLEEPorIDLEMode.

WhenLVDfunctionisenabled,itisrecommencedtoclearLVDflagfirst,andthenenablesinterrupt

functiontoavoidmistakeaction.

HT45F75 Datasheet(PDF) 159 Page - Holtek Semiconductor Inc