High power PoE and HDBaseT

Power over Ethernet (PoE) offers convenience, flexibility, and enhanced management capabilities by enabling power to be delivered over the same CAT5 cabling as data. This technology is especially useful for powering IP telephones, wireless LAN access points, cameras with pan tilt and zoom (PTZ), remote Ethernet switches, embedded computers, thin clients and LCDs.

The original IEEE 802.3af-2003 PoE standard provides up to 15.4 W of DC power (minimum 44 V DC and 350 mA) supplied to each device. The IEEE standard for PoE requires Category 5 cable or higher (can operate with category 3 cable for low power levels).

The updated IEEE 802.3at-2009 PoE standard also known as PoE+ or PoE plus, provides up to 25.5 W of power.

Although 2009 standard prohibits a powered device from using all four pairs for power, some vendors have announced products that claim to be compatible with the 802.3at standard and offer up to 51 W of power over a single cable by utilizing all four pairs in the Category 5 cable. The trend for power demands seem to be up.

Compliance to Power-over-Ethernet safety standards is critical when moving beyond 60W (EE Times)and Compliance with POE safety standards is critical when moving beyond 60W (EDN) articles tells that the current generation of standards-based technology enables up to 60 watts of power to be delivered over four pairs of cabling, which also improves efficiency when compared to earlier two-pair solutions. Compliance with POE safety standards is critical when moving beyond 60W.

As the industry moves toward delivering even more power over the CAT5-or-better cabling infrastructure, system designers and network administrators alike, need to understand various emerging technology options. Some new options can bring expensive and cumbersome deployment complications and, potentially, safety risks.

Some manufacturers have touted their own 100W-per-port solutions or even 200W/port solutions that are not safe. The use of a standard Ethernet-cabling infrastructure for a single port delivering greater than 100W is simply not safe under the NEC standard. The only safe approach for powering devices over Ethernet cabling is to follow IEEE802.3at-2009 specifications. Moving beyond the LPS requirement (sub-100W/port LPS requirement of IEC 60950-1:2011) to greater-than-100W/port implementations requires that the cables be protected with special flame-resistant conduit. A metal enclosure is required if the total PD load is greater than 100W for information data equipment, or greater than 15W for TV and audio equipment.

One standardized 100W solution is one used by HDBaseT Alliance. HDBaseT Alliance is develops 100W power specifications for products that transport uncompressed, high-bandwidth multimedia content, 100BaseT Ethernet, power, and various control signals through a single LAN cable. The key differences between the HDBaseT-powering approach and those from other independent manufacturers pursuing higher power levels are that it:

  • Complies with the section 33.7.1 of the IEEE802.3at-2009 standard, which mandates that all PSEs conform to International Electrotechnical Commission (IEC) 60950-1:2001 specifications including classification as a Limited Power Source (LPS) carrying no more than 100 volt-ampere (VA) – or 100W – per port without the need for special over-current protection devices, and
  • Performs Powered Device (PD) detection followed by PD classification to determine a PD’s consumed power level prior to its ignition.

In a typical HDBaseT implementation, the PSE is installed and powered by a 50 to 57-volt DC power supply, and all PDs receive power directly over the HDBaseT link across all four pairs of CAT5-or-better cables. Additionally, core PoE technology has been enhanced for HDBaseT to use a 1 amp current for every two cabling pairs, 3-event classification to identify compliant PSEs, and identify the cable length/resistance (draw more power when required not exceeding 100W, rather than assuming a worst-case cabling infrastructure at all times). This enables HDBaseT technology to transfer of up to 100W of continuous DC power, per port, from one side of the HDBaseT link to the other.

HDBaseT is fully backwards-compatible with the IEEE802.3at-2009 PoE specification. HDBaseT also does not infringe on any of the mandated PoE safety requirements.

HDBaseT’s ability to deliver up to 100W of power (over 100m, via a single LAN cable, without any additional power source) is actually very nicely aligned with trends in energy usage and demand. The power level is more than adequate for supporting today’s typical 40-inch LED TV, which requires 70W of power. It is expected that both LCD and LED TV monitors will soon be averaging approximately one watt of power consumption per inch of screen size. Regardless of screen size EnergyStar™ 6.0 is targeting a cap of 85 W for all screen sizes.

PoE continues to evolve and offer an even wider variety of high-value power-delivery and management capabilities.


  1. Tomi Engdahl says:

    Valens Takes to Untangling and Untwisting Connected Cars

    High-end cars are some of the most complex machines in the world, with miles of wires linking more than a hundred electronic control units powering everything from windshield wipers to digital speedometers. This is all programmed with millions more lines of code than a fighter jet.

    Valens started out over a decade ago selling networking chips for professional audio and visual devices. But now it is trying to use the same technology to recreate the car’s connective tissue. Its chips encode data so that they can traverse the car’s network over a single unshielded twisted pair cable, replacing many others to reduce cost and weight.

    “The car is becoming like an advanced data center,” said Micha Risling, vice president of Valens’ automotive business, only two years old but already selling a series of chipsets. The comparison works because the cameras, radar, and other sensors in a fully driverless vehicle could discharge more than four terabytes of data every hour and a half of driving.

    To handle it all, Valens is betting on HDBaseT, a standard it invented to transmit uncompressed audio and video, control, Ethernet, USB, and a hundred watts of power simultaneously. It can do this over a single copper cable, which does not have the thick, expensive insulation of traditional cables. That way, it can be tucked into tight spaces in cars.

    Along with Samsung and Sony, the chipmaker turned HDBaseT into a standard in 2010.

    over a copper cable up to 328 feet

    But last year, Daimler said that it would use HDBaseT to connect its infotainment, telematics, and advanced driver assistance systems. Valens’ chief executive, Dror Jerushalmi, said that Daimler would start using it in production cars by 2020. GM, which sits on the alliance’s board, declined to comment on whether it planned to use HDBaseT.

    With the money, Valens can expand its product line to compete with bigger rivals like Marvell and Broadcom, which makes networking chips for Ethernet that – like HDBaseT – work with a single unshielded copper cable.

    “The automotive industry will not have a choice but to move to a centralized approach, simply given that so much processing power is needed. And again, the raw data will have to be processed differently to be used in different clusters,” said Risling in a recent interview. “The sensors really should be as dumb as possible.”

    “Moreover, HDBaseT is not limited to point-to-point topologies and can also support daisy-chaining as well as multi-hop switching and [in that way] reduces the connectivity bottlenecks towards the main ECUs,” he said. “Our ability to support multi-streams over a single channel opens the door for advanced cost-effective interfacing options with other chips in the system.”

    Valens can also deal with electromagnetic interference that leaks out of cables and can cripple performance. The company’s chips can monitor and cancel noise. It also shorted the range of HDBaseT to 50 feet so that cables could transmit at lower frequencies, which can better resist interference.

  2. Tomi Engdahl says:

    Next Ethernet Alliance PoE Plugfest to provide critical support for Power over Ethernet certification program

    The Ethernet Alliance, a global consortium dedicated to the continued success and advancement of Ethernet technologies, has announced details of its next plugfest. Dedicated to pre-standard testing of Power over Ethernet (PoE) technologies against Draft 3.2 of the IEEE P802.3bt standard, the event will be held the week of February 12, 2018, at the University of New Hampshire InterOperability Laboratory (UNH-IOL) in Durham, N.H. Open to Ethernet Alliance members, component developers, system providers, and test equipment manufactures will benefit from participation in this PoE plugfest. Test results will be important to both the ongoing development of the IEEE’s PoE standard and the second generation of the Ethernet Alliance’s PoE Certification Program.

    Per an Ethernet Alliance statement, “As the range of PoE-enabled devices and applications expands and diversifies, the need for additional power is becoming more urgent. With emerging devices and applications requiring increased amounts of power, the IEEE P802.3bt standard is being developed to allow delivery of up to 90 watts of power via existing Ethernet cabling. With the specification’s ratification expected in September of 2018, the Ethernet Alliance is hosting a members-only interoperability plugfest to test equipment to perform pre-standard testing against the IEEE P802.3bt draft standard. Findings will be shared with the IEEE P802.3bt Task Force, providing the group with valuable insight; data gathered during the event will also be leveraged for the second generation of the Ethernet Alliance’s PoE Certification program. This Ethernet Alliance plugfest will allow the industry to get ahead of intensifying interest in advanced PoE solutions, opening the door to new market opportunities.”


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