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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： | 11/30页 |
| 文件大小： | 414K |
| 代理商： | LTC4266IUHF#PBF |
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LTC4266
4266fa
ApplicAtions inForMAtion
capacitance(>10μF)asthedetectionsignature.Notethat
PDsinthisrangeofcapacitancearedefinedasinvalid,so
aPSEthatdetectslegacyPDsistechnicallynoncompliant
withtheIEEEspec.
TheLTC4266canbeconfiguredtodetectthistypeoflegacy
PD.Legacydetectionisdisabledbydefault,butcanbe
manuallyenabledonaper-portbasis.Whenenabled,the
portwillreportdetectgoodwhenitseeseitheravalidIEEE
PDorahigh-capacitancelegacyPD.Withlegacymode
disabled,onlyvalidIEEEPDswillberecognized.
CLASSIFICATION
802.3afClassification
APDcanoptionallypresentaclassificationsignatureto
thePSEtoindicatethemaximumpoweritwilldrawwhile
operating.TheIEEEspecificationdefinesthissignatureas
aconstantcurrentdrawwhenthePSEportvoltageisinthe
VCLASSrange(between15.5Vand20.5V),withthecurrent
levelindicatingoneof5possiblePDclasses.Figure14
showsatypicalPDloadline,startingwiththeslopeof
the25ksignatureresistorbelow10V,thentransitioning
totheclassificationsignaturecurrent(inthiscase,Class
3)intheVCLASSrange.Table3showsthepossibleclas-
sificationvalues.
Table3.ClassificationValues
CLASS
RESULT
Class0
NoClassSignaturePresent;TreatLikeClass3
Class1
3W
Class2
7W
Class3
13W
Class4
25.5W(Type2)
Ifclassificationisenabled,theportwillclassifythePD
immediatelyafterasuccessfuldetectioncycleinsemi-auto
orautomodes,orwhencommandedtoinmanualmode.It
measuresthePDclassificationsignaturebyapplying18V
for12ms(bothvaluestypical)totheportviatheOUT
npin
andmeasuringtheresultingcurrent;itthenreportsthe
discoveredclassintheportstatusregister.IftheLTC4266
wasresetwiththeAUTOpinhighandtheportisinauto
mode,itwilladditionallyusetheclassificationresulttoset
theICUTandILIMthresholds.SeethePower-OnResetand
theAUTO/MIDPinsectionformoreinformation.
Theclassificationcircuitryisdisabledwhentheportis
initiallypoweredupwiththeAUTOpinlow,inshutdown
mode, or when the corresponding class enable bit is
cleared.
802.3at2-EventClassification
The802.3atspecdefinestwomethodsofclassifyinga
Type2PD.
OnemethodaddsextrafieldstotheEthernetLLDPdata
protocol;althoughtheLTC4266iscompatiblewiththis
classification method, it cannot perform classification
directly since it doesn’t have access to the data path.
LLDPclassificationrequiresthePSEtopowerthePDas
astandard802.3af(Type1)device.Itthenwaitsforthe
hosttoperformLLDPcommunicationwiththePDand
updatethePSEportdata.TheLTC4266supportschang-
ingtheILIMandICUTlevelsonthefly,allowingthehost
tocompleteLLDPclassification.
Thesecond802.3atclassificationmethod,knownas2-
eventclassificationorping-pong,isfullysupportedbythe
LTC4266.AType2PDthatisrequestingmorethan13W
willindicateClass4duringnormal802.3afclassification.
IftheLTC4266seesClass4,itforcestheporttoaspeci-
fiedlowervoltage(calledthemarkvoltage,typically9V),
pausesbriefly,andthenre-runsclassificationtoverifythe
Class4reading(Figure1).Italsosetsabitinthehigh
VOLTAGE (VCLASS)
0
CURRENT
(mA)
60
50
40
30
20
10
0
5
10
15
20
4266 F13
25
TYPICAL
CLASS 3
PD LOAD
LINE
48mA
33mA
PSE LOAD LINE
23mA
14.5mA
6.5mA
CLASS 4
CLASS 2
CLASS 1
CLASS 0
CLASS 3
OVER
CURRENT
Figure13.PDClassification
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相关代理商/技术参数 |
参数描述 |
|---|---|
| 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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