Datasheet

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What is PoE?
Theseeminglyuniversalnetworkconnection,twisted-pairEthernetcable,has
anotherroletoplay,providingelectricalpowertolow-wattageelectricaldevices
PoweroverEthernet(PoE)wasratifiedbytheInstituteofElectricalandElectronic
Engineers(IEEE)inJune2000asthe802.3af-2003standard.Itdefinesthe
specificationsforlow-levelpowerdelivery—roughly13wattsat48VDC—
overtwisted-pairEthernetcabletoPoE-enableddevicessuchasIPtelephones,
wirelessaccesspoints,Webcameras,andaudiospeakers.
Recently,thebasic802.3afstandardwasjoinedbytheIEEE802.3atPoEstandard,
ratifiedinSeptember,2009,whichsuppliesupto25wattstolarger,more
power-hungrydevices.802.3atisbackwardscompatiblewith802.3af.
How does PoE work?
Thewayitworksissimple:EthernetcablethatmeetsCAT5(orbetter)
standardsconsistsoffourtwistedpairsofcable,andPoEsendspower
overthesepairstoPoE-enableddevices.Inonemethod,twowirepairs
areusedtotransmitdata,andtheremainingtwopairsareusedfor
power.Intheothermethod,poweranddataaresentoverthesamepair.
Whenthesamepairisusedforbothpoweranddata,thepowerand
datatransmissionsdon’tinterferewitheachother.Becauseelectricity
anddatafunctionatoppositeendsofthefrequencyspectrum,they
cantraveloverthesamecable.Electricityhasalowfrequencyof60Hz
orless,anddatatransmissionshavefrequenciesthatcanrangefrom
10millionto100millionHz.
PoE Solutions
Ethernet
Ethernet
Switch
PSE Unit
(LBPS01A-KIT)
Standard Unit
(LBPS01A-KIT)
Voice-Grade Copper Pair: 100/60 Mbps at 500 ft. (152.4 m)/
28/0.3 Mbps at 4000 ft. (1219 m)
LAN
LAN
PoE Power
LBPS01A-KIT
Ehternet Switch
PoE Repeater (LPR110)
PoE Repeater (LPR110)
PoE Device
PoE Power PoE Power PoE Power
100 m 100 m 100 m
L P R110
Basic structure.
TherearetwotypesofdevicesinvolvedinPoEconfigurations:Power
SourcingEquipment(PSE)andPoweredDevices(PD).
PSEs,whichincludeend-spanandmid-spandevices,providepowertoPDs
overtheEthernetcable.APoEPDaccesspointderivesitspowerfromthe
PSEEthernetbackhaullink.PDsarepiecesofequipmentlikesurveillance
cameras,sensors,wirelessaccesspoints,andotherdevicesthat
receive power via PoE.
WhenaPDispluggedin,itidentifiesitselfasaPoEdevicewitha
25-kilo-ohmresistorbetweenthepoweredpairs.IfthePSEdetects
25-kilo-ohmresistance,itsendspower;itifdetectshigherorlower