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TemperatureRegulationandThermalProtection
ChargeTimerOperation
t
(chg)
K
(tmr)
R
(tmr)
(5)
t
(chg
treg)
t
(chg)
V
(设置)
V
(设置
reg)
(6)
V
(设置
treg)
I
(输出)
R
(设置)
K
(设置)
(7)
bq24030,bq24031,bq24032,
bq24032a,bq24035,bq24038,bq24039
SLUS618C–AUGUST2004–REVISEDJUNE2005
beimplementedbyaresistordividerbetweentheacinputandgroundwiththepselpintiedbetweenr1(顶
电阻)andr2(resistortoground).theresistorvaluesarechosensuchthatthedividervoltagewillbeat1v
(pselthreshold)whentheachasdroppedtoitscriticalvoltage(userdefined).aninternal~280-k
Ω
resistoris
appliedwhenpsel<1v,toprovidehysteresis.chooser2between10k
Ω
and60k
Ω
andV
(交流-核心的)
在
3.5vand4.5v.r1canbefoundusingthefollowingequation:
r1=r2(v
(交流-核心的)
–1v);v
(交流-重置)
=1+r1(r2+280k)/(280k×r2);
例子:ifr2=30k
Ω
andV
(交流-核心的)
=4v;r1=30k
Ω
(4v–1v)=90k
Ω
,v
(交流-重置)
=1+90k(30k+280
k)/(280k×30k)=4.32v.因此,fora90k
Ω
/30k
Ω
分隔物,thebiasonpselwouldswitchpowerfromacto
usb(usbpg=l)whenthevacdroppedto4v(independentofv
BAT
)andswitchesbackwhenthevac
recoversto4.32v.看Figure6通过Figure10.
inordertomaximizechargerate,thebqtiny-iiifeaturesajunctiontemperatureregulationloop.ifthepower
dissipationoftheICresultsinajunctiontemperaturegreaterthantheT
j(reg)
门槛,thebqtiny-iiithrottles
backonthechargecurrentinordertomaintainajunctiontemperaturearoundtheT
j(reg)
门槛.toavoid
falsetermination,theterminationdetectfunctionisdisabledwhileinthismode.
thebqtiny-iiialsomonitorsthejunctiontemperature,t
J
,ofthedieanddisconnectstheoutpinfromacor
USBinputsifT
J
exceedsT
(shtdwn)
.thisoperationcontinuesuntilt
J
fallsbelowT
(shtdwn)
bythehysteresislevel
specifiedinthespecificationtable.
thebatterysupplementmodehasnothermalprotection.theq2fetcontinuestoconnectthebatterytothe
输出(系统),ifinputpowerisnotsufficient;不管怎样,ashort-circuitprotectioncircuitlimitsthebattery
dischargecurrentsuchthatthemaximumpowerdissipationofthepartisnotexceededundertypicaldesign
情况.
asasafetybackup,thebqtiny-iiimonitorsthechargetimeinthechargemode.iftheterminationthresholdis
notdetectedwithinthetimeperiod,t
(chg)
,thebqtiny-iiiturnsoffthechargerandenunciatesfaultonthe
stat1andstat2pins.theresistorconnectedbetweenthetmrandvss,r
TMR
,determinesthetimerperiod.
TheK
(tmr)
parameterisspecifiedinthespecificationstable.inordertodisablethechargetimer,eliminater
TMR
,
connectthetmrpindirectlytotheldopin.notethatthisactioneliminatesallsafetytimers,使不能运转
末端,andalsoclearsanytimerfault.tmrpinshouldnotbeleftfloating.
whileinthethermalregulationmodeordppmmode,thebqtiny-iiidynamicallyadjuststhetimerperiodinorder
toprovidetheadditionaltimeneededtofullychargethebattery.thisproprietaryfeatureisdesignedtoprevent
againstearlyorfalsetermination.themaximumchargetimeinthismode,t
(chg-treg)
,iscalculatedby
Equation6.
Notethatbecausethisadjustmentisdynamicandchangesastheambienttemperaturechangesandthecharge
levelchanges,thetimerclockisadjusted.itisdifficulttoestimateatotalsafetytimewithoutintegratingthe
aboveequationoverthechargecycle.因此,understandingthetheorythatthesafetytimeisadjusted
inverselyproportionatelywiththechargecurrentandthebatteryisacurrent-hourrating,thesafetytime
dynamicallyadjustsappropriately.
TheV
(设置)
parameterisspecifiedinthespecificationstable.v
(设置-treg)
isthevoltageontheISETpinduringthe
thermalregulationordppmmodeandisafunctionofchargecurrent.(notethatchargecurrentisdynamically
adjustedduringthethermalregulationordppmmode.)
Alldeglitchtimesalsoadjustedproportionallytot
(chg-treg)
.
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