A BALANCING ARRANGEMENT FOR FOUR PAIR POWER OVER ETHERNET (20-Dec-2009)

TECHNICAL FIELD

[0001]                           The present invention generally relates to the field of power delivered over communication cabling and more particularly to a balancing arrangement for power delivered over two parallel channels.

BACKGROUND OF THE INVENTION

[0002]                           The growth of local and wide area networks based on Ethernet technology has been an important driver for cabling offices and homes with structured cabling systems having multiple twisted wire pairs.  The ubiquitous local area network, and the equipment which operates thereon, has led to a situation where there is often a need to attach a network operated device for which power is to be advantageously supplied by the network over the network wiring.  Supplying power over the network wiring has many advantages including, but not limited to; reduced cost of installation; centralized power and power backup; and centralized security and management.

[0003]                           Several patents addressed to this issue exist including: U.S. Patent S/N 6,473,608 issued to Lehr et al., and U.S. Patent S/N 6,643,566 issued to Lehr et al., the entire contents of both of which are incorporated herein by reference.  Furthermore a standard addressed to the issue of powering remote devices over an Ethernet based network, known as Power over Ethernet (PoE), has been published as IEEE 802.3af – 2003, whose contents are incorporated herein by reference.  A device receiving power over the network wiring is referred to as a powered device (PD) and the powering equipment delivering power into the network wiring for use by the PD is referred to as a power sourcing equipment (PSE).  The above mentioned standard is limited to a PD having a maximum power requirement during operation of 12.95 watts. Power can be delivered to the PD either directly from the switch/hub known as an endpoint PSE or alternatively via a midspan PSE.  Unfortunately, no provision has been made in the above standard for PDs requiring power in excess of the above maximum power requirement. 

[0004]                           In order to meet growing power demands, in particular demands for PDs drawing in excess of 12.95 watts, a task force entitled "IEEE 802.3at DTE Power Enhancements Task Force" has been formed, which is in the process of producing a higher power standard.  While the task force has not yet finalized its recommendations, it appears that the proposed high power standard will allow for increased current and voltage as compared to the IEEE 802.3af – 2003. 

[0005]                           U.S. Patent S/N 7,492,059 issued

February 17, 2009