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Design Features
Realizing the PoE+ Future
by Matt Tyler
ON Semiconductor Inc.
Power over Ethernet (PoE) has allowed communication and power infrastructure to be combined, significantly reducing hardware installation problems and curbing the required investment, as well as bringing greater functionality and improved flexibility to a plethora of different applications. The recent ratification of IEEE802.3at (PoE+) has the potential to progress this technology still further. ON Semiconductor’s Matt Tyler looks at the implications of this higher power standard, and details the size, cost and performance challenges that lie ahead.
Using only standard CAT-5 data cables, thanks to PoE it has for several years now been possible to connect Powered Devices (PD), such as IP phones, wireless access points, security cameras and various handheld terminals to Power Sourcing Equipment (PSE). The proliferation of this technology has, until this stage, been somewhat restricted though by the output power that could be handled. The IEEE802.3at standard is able to support power levels of up to 30W, compared with the 13.4W offered by the previous IEEE 802.3af version. This will expand the number of products/devices that can profit from PoE and help to satisfy the growing need for greater levels of power.
Application opportunities
A wide array of mainstream consumer oriented products like home/business automation panels, netbook computers and low power laptop models have power requirements that conform with PoE+. As a result a basic docking station consisting of nothing more than a RJ45 connector could be utilized for power distribution. Public information kiosks and point of sale terminals would also benefit greatly from having to forego a dedicated power connection. These units will often have heavy power demands due to their flat panel LCD displays, embedded computing platforms and printer systems, but many will be able to run off a 25 W supply (or the 50W made possible be connected through spare pairs). Wireless infrastructure is also a huge potential growth area for PoE. Access points for WiFi and WiMax transmission have to be connected back to a router, switch, or primary network connection. The additional power delivery that IEEE802.3at permits would greatly simplify deployment, again needing nothing more than a RJ45 interconnect. Another wireless application activity that could gain from the support of high power PoE is the roll out of femto/picocells. These small-scale access points allow mobile communication coverage in non-traditional locations (such as in large buildings) as well as supplementing the existing coverage in high population areas.
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