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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： | 7/30页 |
| 文件大小： | 414K |
| 代理商： | LTC4266IUHF#PBF |
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LTC4266
4266fa
operAtion
Figure10.PowerOverEthernetSystemDiagram
4266 F10
S1B
SMAJ58A
0.22F
100V
X7R
1F
100V
X7R
Tx
Rx
Tx
SMAJ58A
58V
DATA PAIR
VEE SENSE GATE OUT
VDD
INT
SCL
SDAIN
SDAOUT
0.25
IRFM120A
SPARE PAIR
1/4
LTC4266
DGND
AGND
I2C
3.3V
INTERRUPT
–48V
CAT 5
20 MAX
ROUNDTRIP
0.05F MAX
RJ45
4
5
4
5
1
2
1
2
3
6
3
6
7
8
7
8
RJ45
1N4002
4
1N4002
4
PSE
PD
RCLASS
–48VIN
PWRGD
–48VOUT
LTC4265
GND
DC/DC
CONVERTER
5F ≤ CIN
≤ 300F
+
–
VOUT
GND
0.1F
Overview
PoweroverEthernet,orPoE,isastandardprotocolfor
sending DC power over copper Ethernet data wiring.
TheIEEEgroupthatadministersthe802.3Ethernetdata
standardsaddedPoEpoweringcapabilityin2003.This
originalPoEspec,knownas802.3af,allowedfor48VDC
poweratupto13W.Thisinitialspecwaswidelypopular,
but 13W was not adequate for some requirements. In
2009,theIEEEreleasedanewstandard,knownas802.3at
orPoE+,increasingthevoltageandcurrentrequirements
toprovide25Wofpower.
TheIEEEstandardalsodefinesPoEterminology.Adevice
thatprovidespowertothenetworkisknownasaPSE,or
powersourcingequipment,whileadevicethatdrawspower
fromthenetworkisknownasaPD,orpowereddevice.
PSEs come in two types: Endpoints (typically network
switchesorrouters),whichprovidedataandpower;and
Midspans,whichprovidepowerbutpassthroughdata.
MidspansaretypicallyusedtoaddPoEcapabilitytoexisting
non-PoEnetworks.PDsaretypicallyIPphones,wireless
accesspoints,securitycameras,andsimilardevices,but
couldbenearlyanythingthatrunsfrom25Worlessand
includesanRJ45-stylenetworkconnector.
TheLTC4266isathird-generationquadPSEcontroller
thatimplementsfourPSEportsineitheranendpointor
midspandesign.Virtuallyallnecessarycircuitryisincluded
toimplementaIEEE802.3atcompliantPSEdesign,requir-
ingonlyanexternalpowerMOSFETandsenseresistorper
channel;theseminimizepowerlosscomparedtoalterna-
tivedesignswithon-boardMOSFETsandincreasesystem
reliabilityintheeventasinglechannelisdamaged.
PoEBasics
CommonEthernetdataconnectionsconsistoftwoorfour
twistedpairsofcopperwire(commonlyknownasCAT-5
cable),transformer-coupledateachendtoavoidground
loops.PoEsystemstakeadvantageofthiscouplingar-
rangementbyapplyingvoltagebetweenthecenter-taps
ofthedatatransformerstotransmitpowerfromthePSE
tothePDwithoutaffectingdatatransmission.Figure10
showsahigh-levelPoEsystemschematic.
Toavoiddamaginglegacydataequipmentthatdoesnot
expecttoseeDCvoltage,thePoEspecdefinesaprotocol
that determines when the PSE may apply and remove
power.ValidPDsarerequiredtohaveaspecific25kΩ
common-moderesistanceattheirinput.WhensuchaPD
isconnectedtothecable,thePSEdetectsthissignature
resistanceandturnsonthepower.WhenthePDislater
disconnected,thePSEsensestheopencircuitandturns
poweroff.ThePSEalsoturnsoffpowerintheeventofa
currentfaultorshortcircuit.
WhenaPDisdetected,thePSEoptionallylooksfora
classificationsignaturethattellsthePSEthemaximum
powerthePDwilldraw.ThePSEcanusethisinformation
toallocatepoweramongseveralports,policethecurrent
consumptionofthePD,ortorejectaPDthatwilldraw
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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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