ADC 6021 Dokumentacja Pobierz pdf (Strona 70)

MYXPM6021*

Revision 1.1 - 10/21/14

*Advanced information. Subject to change without notice.

MYXPM6021*

Form #: CSI-D-685 Document 011

12 Power Source Detection

12.1 Overview

TherearethreeinputsupplysourcesthatcanbedetectedbyMYXPM6021:VBAT,VDCIN_SENSEandVBUS_SENSE

referringtothebattery,ACadapterandUSBconnector,respectfully.Forallpowersourcesdedicatedcomparatorsare

usedforthepowerdetection.Alldetectorsincludede-bouncelogicwithanominaltimeperiodof100mswhichcanbe

disabledbysoftware.

12.2 VBAT Power Source Detection

12.2.1 Battery Voltage Monitor & Removal / Insertion Detection

Figure 31: VBAT Input Detection

ItisadvantageoustouseabatterypackwithintegratedBSIresistance(pull-downinthebatterypackindicatingtheID

orsize)asitoffersanadvancedwarningonbatteryremovalevents.Suchanimplementationisnecessarytomeetthe

SDWN_BsignaltimingrequirementofsomemodemSIMcards.

Duringnormaloperation(batterypackpresent/inserted),theBSIresistanceinthebatterypackpullstheanalogvoltageat

theBATIDpintoanintermediatevoltage,betweenVREF(ADCbiasvoltagefromtheVREFBpin)andGND.WhentheBSI

terminalofthebatterypacknolongermakescontact(asonremoval),BATIDisimmediatelypulledhightoVREFbythe

measurementresistanceontheplatform,RMBI(30KΩto200KΩ).

WhileusingtheBATIDcomparatorsensingthebatteryinsertion/removal,thereareseparatede-bouncetimesforinsertion

andremoval.Thisprovidessufcientpower-uptimeforUSBPHYrelatedcomponentsoninsertion,ontheotherhandit

allowsaquickdetectiontimeofbatteryremovalforSIMcardearlywarning(viaSDWN_B).

NotethatBAITDcomparatorisgivingalowoutputifthebatteryisremoved.

WhenBATRMSRC=1(usingBATIDcomparator),thethresholdsinthetablebelowdenethepresent/absentvoltagetrip

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ADC 6021 Dokumentacja Strona 70