Non-standard implementations Power over Ethernet

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1 non-standard implementations

1.1 cisco
1.2 linear technology
1.3 microsemi
1.4 passive





non-standard implementations
cisco

some cisco manufactured wlan access points , ip phones supported proprietary form of poe many years before there ieee standard delivering poe. cisco s original poe implementation not software upgradeable ieee 802.3af standard. cisco s original poe equipment capable of delivering 10 w per port. amount of power delivered negotiated between endpoint , cisco switch based on power value added cisco proprietary cisco discovery protocol (cdp). cdp responsible dynamically communicating voice vlan value cisco switch cisco ip phone.


under cisco s pre-standard scheme, pse (switch) send fast link pulse (flp) on transmit pair. pd (device) connects transmit line receive line via low pass filter. , pse gets flp in return. , common mode current between pair 1 , 2 provided resulting in 48 v dc , 6.3 w default of allocated power. pd has provide ethernet link within 5 seconds auto-negotiation mode switch port. later cdp message type-length-value tells pse final power requirement. discontinued link pulses shuts down power.


in 2014, cisco created non-standard poe implementation called universal power on ethernet (upoe). upoe can use 4 pairs, after negotiation, supply 60 w.


linear technology

a proprietary high-power development called ltpoe++ using single cat-5e ethernet cable capable of supplying varying levels @ 38.7 w, 52.7 w, 70 w, , 90 w in addition being backwards compatible ieee 802.at.


microsemi

powerdsine, acquired microsemi in 2007, has been selling midspan power injectors since 1999 proprietary power on lan solution. several companies such polycom, 3com, lucent , nortel utilize powerdsine s power on lan.


passive

the common 100 mbit/s passive applications use pinout of 802.3af mode b - dc plus on pins 4 , 5 , dc minus on 7 , 8 (see chart below) , data on 1-2 , 3-6. gigabit passive injectors use transformer on data pins allow power , data share cable , typically compatible 802.3af mode a. in common passive poe system, injector not communicate powered device negotiate voltage or wattage requirements, merely supplies power @ times. passive midspan injectors 12 ports simplify installations. devices needing 5 volts cannot typically use poe @ 5 v on ethernet cable beyond short distances (about 15 feet (4.6 m)) voltage drop of cable becomes significant, 24 v or 48 v 5 v dc-dc converter required @ remote end. passive dc-to-dc injectors exist convert 9 v 36 v dc input power source stabilized 24 v 1 a or 48 v 0.5 a poe feed + on pins 4 & 5 , − on pins 7 & 8. these dc-to-dc poe injectors used in various telecom applications.








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