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参数资料
| 型号： | LTC4266IUHF#PBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 电源管理 |
| 英文描述： | POWER SUPPLY MANAGEMENT CKT, PQCC38 |
| 封装： | 5 X 7 MM, LEAD FREE, PLASTIC, MO-220WHKD, QFN-38 |
| 文件页数： | 15/30页 |
| 文件大小： | 414K |
| 代理商： | LTC4266IUHF#PBF |
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LTC4266
4266fa
ApplicAtions inForMAtion
MOSFETFaultDetection
LTC4266PSEportsaredesignedtotoleratesignificant
levelsofabuse,butinextremecasesitispossiblefor
theexternalMOSFETtobedamaged.AfailedMOSFET
mayshortsourcetodrain,whichwillmaketheportap-
peartobeonwhenitshouldbeoff;thisconditionmay
alsocausethesenseresistortofuseopen,turningoff
theportbutcausingtheLTC4266SENSEpintoriseto
anabnormallyhighvoltage.AfailedMOSFETmayalso
shortfromgatetodrain,causingtheLTC4266GATEpin
torisetoanabnormallyhighvoltage.TheLTC4266SENSE
andGATEpinsaredesignedtotolerateupto80Vfaults
withoutdamage.
IftheLTC4266seesanyoftheseconditionsformorethan
180μs,itdisablesallportfunctionality,reducesthegate
drivepull-downcurrentfortheportandreportsaFETBad
fault.Thisistypicallyapermanentfault,butthehostcan
attempttorecoverbyresettingtheport,orbyresetting
theentirechipifaportresetfailstoclearthefault.Ifthe
MOSFETisinfactbad,thefaultwillquicklyreturn,and
theportwilldisableitselfagain.Theremainingportsof
theLTC4266areunaffected.
AnopenormissingMOSFETwillnottriggeraFETBad
fault,butwillcauseatSTARTfaultiftheLTC4266attempts
toturnontheport.
VoltageandCurrentReadback
TheLTC4266measurestheoutputvoltageandcurrent
ateachportwithaninternalA/Dconverter.Portdatais
onlyvalidwhentheportpowerison.Theconverterhas
twomodes:
Slowmode:14samplespersecond,14.5bitsresolution
Fastmode:440samplespersecond,9.5bitsresolution
Infastmode,theleastsignificant5bitsofthelowerbyteare
zeroessothatbitscalingisthesameinbothmodes.
Disconnect
TheLTC4266monitorstheporttomakesurethatthePD
continuestodrawtheminimumspecifiedcurrent.Adis-
connecttimercountsupwheneverportcurrentisbelow
7.5mA(typ),indicatingthatthePDhasbeendisconnected.
IfthetDIStimerexpires,theportwillbeturnedoffand
thedisconnectbitinthefaulteventregisterwillbeset.
IfthecurrentreturnsbeforethetDIStimerrunsout,the
timerresetsandwillstartcountingfromthebeginning
iftheundercurrentconditionreturns.AslongasthePD
exceedstheminimumcurrentlevelmoreoftenthantDIS,
itwillstaypowered.
Althoughnotrecommended,theDCdisconnectfeature
can be disabled by clearing the corresponding enable
bits.Notethatthisdefeatstheprotectionmechanisms
builtintotheIEEEspec,sinceapoweredportwillstay
poweredafterthePDisremoved.Ifthestill-poweredport
issubsequentlyconnectedtoanon-PoEdatadevice,the
devicemaybedamaged.
TheLTC4266doesnotincludeACdisconnectcircuitry,but
includesACdisconnectenablebitstomaintaincompat-
ibilitywiththeLTC4259A.IftheACdisconnectenablebits
areset,DCdisconnectwillbeused.
ShutdownPins
TheLTC4266includesahardwareSHDNpinforeachport.
WhenaSHDNpinispulledtoDGND,thecorresponding
portwillbeshutoffimmediately.Theportremainsshut
downuntilre-enabledviaI2Coradeviceresetinauto
mode.
MaskedShutdown
TheLTC4266providesalowlatencyportsheddingfea-
turetoquicklyreducethesystemloadwhenrequired.By
allowingapre-determinedsetofportstobeturnedoff,
thecurrentonanoverloadedmainpowersupplycanbe
reducedrapidlywhilekeepinghighprioritydevicespow-
ered.Eachportcanbeconfiguredtohighorlowpriority;
alllow-priorityportswillshutdownwithin6.5μsafter
theMSDpinispulledlow.IfmultipleportsinaLTC4266
deviceareshutdownviaMSD,theyarestaggeredbyat
least0.55μstohelpreducevoltagetransientsonthemain
supply.IfaportisturnedoffviaMSD,thecorresponding
detection and classification enable bits are cleared, so
theportwillremainoffuntilthehostexplicitlyre-enables
detection.
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相关代理商/技术参数 |
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| LTC4267 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Quad IEEE 802.3at Power over Ethernet Controller |
| LTC4267-1 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Power over Ethernet IEEE 802.3af PD Interface with Integrated Switching Regulator |
| LTC4267-3 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Power over Ethernet IEEE 802.3af PD Interface with Integrated Switching Regulator |
| LTC4267CDHC | 制造商:Linear Technology 功能描述:Hot Swap Controller 1-CH -57V 16-Pin DFN EP |
| LTC4267CDHC#PBF | 功能描述:IC POE 802.3AF INTERFACE 16-DFN RoHS:是 类别:集成电路 (IC) >> 接口 - 控制器 系列:- 标准包装:2,450 系列:- 控制器类型:SPI 总线至 I²C 总线桥接 接口:I²C，串行，SPI 电源电压:2.4 V ~ 3.6 V 电流 - 电源:11mA 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:24-VFQFN 裸露焊盘 供应商设备封装:24-HVQFN（4x4） 包装:托盘 配用:568-3511-ND - DEMO BOARD SPI TO I2C 其它名称:935286452157SC18IS600IBSSC18IS600IBS-ND |
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