HT45FM2C datasheet(146/171 Pages) HOLTEK

146 / 171 page

Rev. 1.10

146

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Rev. 1.10

147

�a� �0� �01�

HT45FM2C

Brushless DC Motor Flash Type 8-Bit MCU

HT45FM2C

Brushless DC Motor Flash Type 8-Bit MCU

Preliminar�

LVD Operation

TheLowVoltageDetectorfunctionoperatesbycomparingthepowersupplyvoltage,VDD,witha

pre-specifiedvoltagelevelstoredintheLVDCregister.Thishasaspecifiedvoltage3.6V.Whenthe

powersupplyvoltage,VDD,fallsbelowthispre-determinedvalue,theLVDObitwillbesethigh

indicatingalowpowersupplyvoltagecondition.TheLowVoltageDetectorfunctionissupplied

byareferencevoltagewhichwillbeautomaticallyenabled.Whenthedeviceispowereddownthe

lowvoltagedetectorwillremainactiveiftheLVDENbitishigh.AfterenablingtheLowVoltage

Detector,atimedelaytLVDSshouldbeallowedforthecircuitrytostabilisebeforereadingtheLVDO

bit.NotealsothatastheVDDvoltagemayriseandfallratherslowly,atthevoltagenearsthatof

VLVD,theremaybemultiplebitLVDOtransitions.

LVD Operation

VD D

V LV D

LV DE N

LV DO

t LV DS

TheLowVoltageDetectoralsohasitsowninterruptwhichiscontainedwithinoneoftheMulti-

functioninterrupts,providinganalternativemeansoflowvoltagedetection,inadditiontopolling

theLVDObit.TheinterruptwillonlybegeneratedafteradelayoftLVDaftertheLVDObithasbeen

sethighbyalowvoltagecondition.WhenthedeviceispowereddowntheLowVoltageDetector

willremainactiveiftheLVDENbitishigh.Inthiscase,theLVDFinterruptrequestflagwillbe

set,causinganinterrupttobegeneratedifVDDfallsbelowthepresetLVDvoltage.Thiswillcause

thedevicetowake-upfromtheSLEEPorIDLEMode,howeveriftheLowVoltageDetectorwake

upfunctionisnotrequiredthentheLVDFflagshouldbefirstsethighbeforethedeviceentersthe

SLEEPorIDLEMode.

HT45FM2C Datasheet(PDF) 146 Page - Holtek Semiconductor Inc