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Keywords: Power over Ethernet, POE, LEDs, LED lighting, Ethernet, LANs, power sourcing equipment,
PSE, powered device, PD, energy efficiency
APPLICATION NOTE 6141
POE AND LED LIGHTING: THE PERFECT
MATCH
Abstract: This application note explains that Power-over-Ethernet (PoE) is a technology used in wired local
area networks (LANs). PoE delivers power over the same cable that delivers the Ethernet data. Using LED
lighting on a PoE network delivers excellent energy efficiency because it minimizes inefficient power-
conversion stages for LED lights used in a retrofitted, legacy, AC-powered socket. The application note also
explains how powering and controlling LED lights over a PoE network creates the opportunity to use the
LED lights in new and novel ways. Examples are given.
Power-over-Ethernet (PoE) is a technology used in wired Ethernet local area networks (LANs) that delivers
power over the same cable that delivers the Ethernet data. This reduces the number of cables that must be
laid to install a network and power the devices connected to it. It also makes it easier to maintain and adjust
the access ports on the network to meet changing requirements than with traditional wiring. The PoE
standard was originally developed to meet the needs of IT services and is appropriate for a wide range of
network connected devices including IP telephony, IP security cameras, wireless access points, modems,
switches, and other networked products.
Designers and facility managers continue to find new ways to reap the benefits of using PoE networks by
connecting devices that were previously never associated with networks such as LED lighting. The nature
of LED lighting lends itself to naturally leverage the strengths of a PoE installation. Before we explore how
and why LED lighting and PoE networks are a perfect match for each other, we will go over the elements
that make up a PoE network installation.
PoE technology is regulated by the IEEE 802.3 standard. The original PoE standard was released in 2003
and updated in 2009. It specifies that power and communication data be delivered across a single standard
network cable wire (i.e., cat 5) directly to the RJ45 network port of the connected devices. PoE supports
10BASE-T, 100BASE-TX, and 1000BASE-T networks.
The power sourcing equipment (PSE) located in an endspan at the switch/hub, or used in a midspan,
provide power to a connected device on the network referred to as a powered device (PD). An endspan
PSE is an Ethernet switch that includes power within the network cabling. A midspan PSE is a power
injector that resides between a normal Ethernet switch and the PD, and it injects power within the network
cabling without affecting the data. Being able to install PSEs in midspan and endspan configurations
supports legacy networks and offers more control over which network segments are powered.
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