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Keeping an eye on PoE within security end-equipment

Thu, 11/14/2013 - 9:26am
Thomas Lewis, Texas Instruments

Power over Ethernet (PoE) is forecasted to experience one of the highest compounded annual growth rates (CAGR), in the power management IC category, over the next five years.[1] Driven by the demand for ease of installation across multiple end equipment, and lifted by a planned new IEEE standard [2] to ensure interoperability at per port power levels greater than 25.5W at the PD, the technology is poised to experience an explosive growth curve only rivaled by the period shortly after initial introduction in the 2003-2007 timeframe.

Power over Ethernet’s core benefit is delivering a convenient power delivery method dealing with large scale system deployments (like WAPs, cameras and IP phones) at lower installation costs compared with traditional AC installations. One of the original cons of the standard, when it was first published in 2003, was the decision to limit the current sent across the CAT-5 cable to 0.35A over two pairs (instead of the possible four). Combined with other parameters of the standard, this limited the total power delivered at the end of a 100m cable to 13W.

Four years later, under pressure to extend PoE’s ease-of-installation to higher power levels (and given enough deployments and data to ensure safety), the IEEE committee began work to publish the current “at” standard which raised that level to 0.6A. Well, the clock continues to tick and here we are again – four years after the last revision looking to raise power levels of PoE once again. (Note: The IEEE is currently forecasting a publication date of 2Q16.)

Applications
In addition to forecasted growth in traditional PoE end equipment spaces of IP phones, IP security cameras and wireless access points (WAP), the ability to push PoE power levels to 40W, 60W, or even 80W is opening entirely new load applications for the technology. Some of the possibilities, and in many cases – early adopters, are shown in Table 1.

Several of these proposed new applications have the same core characteristic of their PoE predecessors – a centralized data hub connected via Ethernet cable to 4, 8, 12, 24 or 48 system deployments of remote loads.

In addition to this call from new applications, existing PoE end equipment continue to push power boundaries of the existing standard as new features are adopted. With IP phones, the addition of telepresence via built-in monitors is driving the need for power past the 25.5W limitation. WAPs, with their increased need for higher band widths and faster processing times, are becoming more power hungry as well. However, of the traditional PoE end equipment segments, the IP Security system is the one most excited by a proposed push through the 25.5W ceiling. Propelled by a strong indigenous growth of IP Security systems in general, this market is projected to enjoy an outstanding 25-30% growth in PoE IC adoption over the next 5 years.[3]

A remarkable aspect of this market inflection point is that growth is forecast to come from both sides of the cable. On the sourcing side, an increasing number of network video recorder (NVR) vendors are recognizing the value of plug-and-play installations and are pulling PoE sourcing capabilities into the units themselves. Dwindling in number are designs that connect cameras directly to AC power sources and/or very expensive Ethernet switches. As the demand for smaller video security systems become more ubiquitous, the appeal of these turnkey systems continues to grow.

On the delivered side, newer, power-hungry features are finding their way into more main stream models and creating the need for >25.5W loads. These new features include pull from:

1) Increased analytics “at the edge” such as tamper detection and/or motion detection

2) Higher resolution

3) Infrared capability

4) Advanced motor control

5) Internal heating elements (to prevent lens condensation)

Challenges
In order to meet market demand, the IEEE committee plans to adopt the use of power-over-four-pair (4PPoE) delivery. Originally considered in the early days of PoE adoption, but kept out of the standard over concerns regarding cable heating, building installation codes, and overall system efficiency, the committee is revisiting this possible implementation given advancements in technology and the popularity of PoE adoption in general. Some of the bigger challenges the IEEE committee will face as they work through the technical challenges of supporting a minimum of 49W at the load (one of the formal objectives adopted by IEEE 4PPoE Study Group; July 2013) are:

· Defining new identification protocols while maintaining backwards compatibility and maximizing interoperability. Of particular concern to many customers are the ability to:

   o Maintain the existing standard detection of a 25K Ohm resistor

   o Maintain the ability for delivered power to be implemented with one PD interface chip to minimize cost

   o Maintain the ability to have solutions with or without LLDP at both ends of the cable for those customers without extensive software knowledge and/or resourcing

   o Optimize the number of power levels selectable via the physical layer

   o Achieve all of this within the existing 2-finger class events defined in the existing standard

· Reliability of cabling and connectors at higher current levels over time

· Avoid potential for current imbalance between the two pairs and resulting negative impact on the data transformer

In addition to these system level challenges, semiconductor vendors will need to manage the increased power demands at an IC level. Implementing new, and more precise, ways of sensing current will take center stage along with working in tandem with, or incorporating, lower RDSON MOSFETs. The list of technical challenges is daunting. With that said, the business opportunity is equally unquestionable. For more discussion on this topic, and updates from the IEEE committee, please visit Texas Instruments’ biweekly PoE dialogue on the Power House blog.


References

1. IHS, “The World Market for Power Management and Driver ICs – 2012,” Table 2.2, page 28

2. IEEE802.3bt, IEEE Website: http://www.ieee802.org/3/4PPOE/

3. IHS; “The World Market for Power Management and Driver ICs – 2012,” Table 2.59, page 118

4. For more information on POE, visit: www.ti.com/poe


About the author

Thomas Lewis is a Systems & Applications Manager supporting Power over Ethernet (both sides of the cable, PSE and PD), USB controllers and eFuse/HotSwap ICs. Thomas received his BA from the University of Pittsburgh, his MBA from the University of Notre Dame, and has been working at TI since before the first PoE standard was published. Thomas can be reached at ti_thomaslewis@list.ti.com.

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