Overview of The PoE Technology

Power over Ethernet (PoE), referred to IEEE802.3af “ Carrier Sense Multiple Access with Collision detection (CSMA/CD) Access Method and Physical Layer Specification. Amendment: Data Terminal Equipment (DTE) Power via Media Dependent Interface ”, is an extension to existing Ethernet standard and was approved in June 2003. It defines how to integrate power into a data cable while keeping data integrity and ensuring safety of the network. As shown in Figure 1, a typical PoE installation involves two major components, the Power Sourcing Equipment (PSE) and the Powered Device (PD). All PoE devices are compatible in one of these two components when connected through a standard CAT5 cabling. Normally, the power applied by PoE is at 48V with a maximum current of 350mA which would supply 13W of power to drive various kinds of devices, such as VoIP phones, wireless AP, IP security industrial cameras, bar code readers and so on.
VoIP PhoneWireless APIP CameraBar Code Reader Figure 2. Examples of Powered Device sales@korenix.com

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