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Power-over-Ethernet: IEEE 802.3af Draft

Posted by Hemos on from the like-ma-no-extra-wires dept.

SkewlD00d writes "Want power (~10W) and your fat 10/100Mbps pipe (1Gbps maybe) on the SAME jack. Surf the web and recharge your handheld w/o finding its clunky base/transformer, home automation, and control systems are just some of the possibilities. Using suitable hubs/switches or dongle, power can be provided over unused pairs, or possibly raise the signal offset above DC, X10-style (no link, u know why). See IEEE 802.3af DTE Power via MDI Task Force. Maxim (not that one :o) already has some goodies. They have schematics for 8.25W/12.5W single-output and 14.2W triple-output 802.3af PSU. Try FindChips if you're looking for them; they're in production and are NOT vapor-ware!"

3 of 172 comments (clear)

  1. Great for powering wireless APs by kriegsman · · Score: 5, Interesting

    Here's a useful how-to on powering wireless base stations using Power-Over-Ethernet (POE). Several wireless vendors already sell POE kits for wireless APs. Here's a POE kit for the AirPort.

    Power+Ethernet over one wire is a great combination for settting up APs, because many of the interesting places to put a wireless access point (e.g., in the attic, by the pool, in the middle of the ceiling) may not have a power outlet nearby, or you may simply not want to run two sets of wires (AC power + ethernet) to the location.

    -Mark

  2. Re:Great, I need an electrician to install Etherne by swb · · Score: 5, Insightful

    While overstated, I wonder what the power safety capabilities are in some of the already-available implementations of this.

    I'm not as worried about shock, but about unintentional shorts burning out switch ports or misplugged equipment. It'd be awesome if there were software-resettable breakers on the switches so that you wouldn't lose line cards. I had the misfortune of accidentally shorting a couple of Merlin phone system ports and those ports are dead, dead, dead forever.

    I also wonder what it does to existing wiring codes and cable plants if any significant power starts to become present on data cabling. It'd suck to become dependent on this power only to have data cabling drops become more costly due to tighter code restrictions on where they can be placed.

  3. Chips Available at Linear by Syris · · Score: 5, Informative
    Linear Technology makes some Power-Over-Ethernet IC's. Like this one.

    The Linear typical app seems to be much smaller, with fewer external components because it's actually optimized for the application.

    The Maxim chips appear to be generic hot-swap IC's not optimized for power-over-ethernet. Using slashdot is an interesting way to publish an app-note and get some publicity.