ETIC 2230 Guia do Utilizador descarregar pdf (Página 129)

Rev. 1.10 128 November 14, 2014 Rev. 1.10 129 November 14, 2014

HT66FW2230

Wireless Charger A/D Flash 8-Bit MCU

LVD Operation

TheLowVoltageDetectorfunctionoperatesbycomparingthepowersupplyvoltage,V

,witha

pre-speciedvoltagelevelstoredintheLVDCregister.Thishasarangeofbetween2.0Vand4.0V.

Whenthepowersupplyvoltage,V

,fallsbelowthispre-determinedvalue,theLVDObitwillbe

sethighindicatingalowpowersupplyvoltagecondition.TheLowVoltageDetectorfunctionis

suppliedbyareferencevoltagewhichwillbeautomaticallyenabled.Whenthedeviceispowered

downthelowvoltagedetectorwillremainactiveiftheLVDENbitishigh.AfterenablingtheLow

VoltageDetector,atimedelayt

LVDS

shouldbeallowedforthecircuitrytostabilisebeforereadingthe

LVDObit.NotealsothatastheV

voltagemayriseandfallratherslowly,atthevoltagenearsthat

ofV

LVD

,theremaybemultiplebitLVDOtransitions.

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LVD Operation

TheLowVoltageDetectoralsohasitsowninterruptwhichiscontainedwithinoneoftheMulti-

functioninterrupts,providinganalternativemeansoflowvoltagedetection,inadditiontopolling

theLVDObit.Theinterruptwillonlybegeneratedafteradelayoft

LVD

aftertheLVDObithasbeen

sethighbyalowvoltagecondition.WhenthedeviceispowereddowntheLowVoltageDetector

willremainactiveiftheLVDENbitishigh.Inthiscase,theLVFinterruptrequestagwillbeset,

causinganinterrupttobegeneratedifVDDfallsbelowthepresetLVDvoltage.Thiswillcausethe

devicetowake-upfromtheSLEEPorIDLEMode,howeveriftheLowVoltageDetectorwakeup

functionisnotrequiredthentheLVFagshouldberstsethighbeforethedeviceenterstheSLEEP

orIDLEMode.

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ETIC 2230 Guia do Utilizador Página 129