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参数资料
| 型号： | LTC4266CGW#TRPBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 电源管理 |
| 英文描述： | POWER SUPPLY MANAGEMENT CKT, PDSO36 |
| 封装： | 0.300 INCH, LEAD FREE, PLASTIC, SSOP-36 |
| 文件页数： | 13/30页 |
| 文件大小： | 414K |
| 代理商： | LTC4266CGW#TRPBF |
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LTC4266
0
4266fa
ApplicAtions inForMAtion
powerstatusregistertoindicatethatitranthesecond
classificationcycle.ThesecondcyclealertsthePDthat
itisconnectedtoaType2PSEwhichcansupplyType2
powerlevels.
2-eventping-pongclassificationisenabledbysettingabit
intheport’shighpowermoderegister.Notethataping-
pongenabledportonlyrunsthesecondclassificationcycle
whenitdetectsaClass4device;ifthefirstcyclereturns
Class0to3,theportassumesitisconnectedtoaType1
PDanddoesnotrunthesecondclassificationcycle.
InvalidType2ClassCombinations
The802.3atspecdefinesaType2PDclasssignatureas
twoconsecutiveClass4results;aClass4followedby
aClass0-3isnotavalidsignature.Inautomode,the
LTC4266willpoweradetectedPDregardlessoftheclas-
sificationresults,withoneexception:ifthePDpresents
aninvalidType2signature(Class4followedbyClass0
to3),theLTC4266willnotprovidepowerandwillrestart
thedetectionprocess.Toaidindiagnosis,theportstatus
registerwillalwaysreporttheresultsofthelastclasspulse,
soaninvalidClass4–Class2combinationwouldreport
asecondclasspulsewasrunintheHighPowerStatus
register(whichimpliesthatthefirstcyclefoundClass4),
andClass2intheportstatusregister.
POWERCONTROL
ExternalMOSFET,SenseRSummary
The primary function of the LTC4266 is to control the
deliveryofpowertothePSEport.Itdoesthisbycontrol-
lingthegatedrivevoltageofanexternalpowerMOSFET
whilemonitoringthecurrentviaanexternalsenseresis-
torandtheoutputvoltageattheOUTpin.Thiscircuitry
servestocoupletherawVEEinputsupplytotheportin
acontrolledmannerthatsatisfiesthePD’spowerneeds
whileminimizingpowerdissipationintheMOSFETand
disturbancesontheVEEbackplane.
TheLTC4266isdesignedtouse0.25senseresistorsto
minimizepowerdissipation.Italsosupports0.5sense
resistors,whicharethedefaultwhenLTC4258/LTC4259A
compatibilityisdesired.
InrushControl
Oncethecommandhasbeengiventoturnonaport,the
LTC4266rampsuptheGATEpinofthatport’sexternal
MOSFETinacontrolledmanner.Undernormalpower-up
circumstances,theMOSFETgatewillriseuntiltheport
currentreachestheinrushcurrentlimitlevel(typically
450mA),atwhichpointtheGATEpinwillbeservoedto
maintainthespecifiedIINRUSHcurrent.Duringthisinrush
period,atimer(tSTART)runs.Whenoutputchargingis
complete,theportcurrentwillfallandtheGATEpinwill
beallowedtocontinuerisingtofullyenhancetheMOSFET
andminimizeitson-resistance.ThefinalVGSisnominally
13V.IfthetSTARTtimerexpiresbeforetheinrushperiod
completes,theportwillbeturnedbackoffandatSTART
faultreported.
CurrentLimit
EachLTC4266portincludestwocurrentlimitingthresholds
(ICUTandILIM),eachwithacorrespondingtimer(tCUT
andtLIM).SettingtheICUTandILIMthresholdsdepends
onseveralfactors:theclassofthePD,thevoltageofthe
mainsupply(VEE),thetypeofPSE(1or2),thesense
resistor(0.5Ωor0.25Ω),theSOAoftheMOSFET,and
whetherornotthesystemisrequiredtoimplementclass
enforcement.
PertheIEEEspec,theLTC4266willallowtheportcur-
renttoexceedICUTforalimitedperiodoftimebefore
removingpowerfromtheport,whereasitwillactively
controltheMOSFETgatedrivetokeeptheportcurrent
belowILIM.Theportdoesnottakeanyactiontolimitthe
current when only the ICUTthresholdisexceeded,but
doesstartthetCUTtimer.ThetLIMtimerstartswhenthe
ILIMthresholdisexceededandcurrentlimitisactive.If
thecurrentdropsbelowtheICUTcurrentthresholdbefore
itstimerexpires,thetCUTtimercountsbackdown,but
at1/16theratethatitcountsup.Thisallowsthecurrent
limitcircuitrytotolerateintermittentoverloadsignalswith
dutycyclesbelowabout6%;longerdutycycleoverloads
willturntheportoff.
ICUTistypicallysettoalowervaluethanILIMtoallowthe
porttotolerateminorfaultswithoutcurrentlimiting.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC4266CIUHF#PBF | 功能描述:IC CONTROLLER PSE QUAD 38-QFN 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 |
| LTC4266CIUHF#TRPBF | 功能描述:IC CONTROLLER PSE QUAD 38-QFN 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 |
| LTC4266CUHF#PBF | 制造商:Linear Technology 功能描述:POE Controller 25.5W 38-Pin QFN EP 制造商:Linear Technology 功能描述:IC POE CONTROLLER 3.3V QFN-38 制造商:Linear Technology 功能描述:IC, POE CONTROLLER, 3.3V, QFN-38; Input Voltage:3.3V; Supply Current:-2.4mA; UVLO:25V; Digital IC Case Style:QFN; No. of Pins:38; Frequency:1MHz; Operating Temperature Min:0C; Operating Temperature Max:70C; MSL:MSL 1 - Unlimited ;RoHS Compliant: Yes |
| LTC4266CUHF#TRPBF | 制造商:Linear Technology 功能描述:POE Controller 25.5W 38-Pin QFN EP |
| LTC4266IGW#PBF | 功能描述:IC CTRLR IEEE 802.3AT 36-SSOP 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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