LinkPower
LPS1000 Adjustable Voltage PoE Switch
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The introduction of network devices that require more than 15.4W such as notebooks, video
phones, PTZ IP cameras, and WiMax base stations, has compelled the IEEE 802.3 workgroup
to develop a new PoE standard that can deliver even more power than defined in the IEEE
802.3af standard. This new standard, IEEE 802.3at, derived in 2004, was designed to deliver
at least 30W per port of inline power. Transmitting more than 15.4W of power per port poses
significant challenges. One such challenge lies in the physical characteristics of copper cabling,
which can overheat or become damaged when transmitting power above certain thresholds.
The IEEE workgroup is exploring different means of transmitting higher levels of power subject
to these limitations. Another challenge is backward compatibility with the IEEE 802.3af
standard. This interoperability could be crucial to the successful adoption of 802.3at. Therefore,
the IEEE is working to make sure that 802.3at-compliant PSEs are able to interoperate with
802.3af powered devices and vice-versa. As a result of these and other implementation
challenges, the IEEE 802.3at standard is not expected to be finalized any time soon.
Proprietary Active PoE
PoE products utilizing proprietary active PoE technology are vendor specific and usually not
interoperable between vendors. Since the install base for proprietary Active PoE is small,
products based on this technology are usually very costly. The following sections omit the
discussion of proprietary Active PoE technology and focuses on pre-standard and standard
PoE technologies.
PoE Architecture
PoE eliminates time, cost and effort required to install separate 110/220 Volts Alternating
Current (VAC) power to the remote PD. Using the power derived from the Ethernet connection
eliminates the need for a localized battery back-up, preventing any data loss or security
breaches. All PD devices can be protected by a single centralized UPS.
