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highpowerZONE Products for the week of March 31, 2008
Akros Silicon Says…
AS1135: Integrated Powered Device Controller Supporting 2-Event Physical Layer Classification per Upcoming IEEE802.3at Power-Over-Ethernet Standard
Includes Seamless Auxiliary Power Support for Down to10V and Integrates Field-Proven Low-Emission, High-Efficiency Dc-Dc Converter
Akros Silicon Inc., a leader in Power-over-Ethernet (PoE) mixed-signal ICs, announced the industry’s first Powered Device (PD) Controller, implementing the 2-Event Physical Layer Classification functionality of the IEEE 802.3at standard (Draft 2.0). This upcoming PoE standard raises the maximum available PD input power to 30W from the previously specified level of 13W in the existing 802.3af standard. The new 30W power level opens up a range of new applications for PoE, including IP Security Cameras with Power, Tilt and Zoom (PTZ) capability, new multi-radio 802.11n Wireless Access Points, WiMax Customer Premise Equipment, SOHO Ethernet Switches, Thin Clients and LCD Displays.
The 2-Event Classification allows the PD to recognize whether it is connected to a Type 1 (802.3af/13W) or Type 2 (802.3at/30W) Power Sourcing Equipment (PSE), and vice-versa. The 2-event Classification informs the IEEE 802.3at compliant PSE that it is safe to increase power delivered to the PD from 13W to 30W. Use of this classification protocol between Type 2 PSE and Type 2 PD enables dynamic negotiation and allocation of power, leading to more efficient system power management.
“While many silicon vendors have been developing and announcing controllers suitable for high power applications for some time, as the first to include support for 2-Event classification in its PD Controller, Akros Silicon has demonstrated its commitment to this growing market,” said Brian Greenberg, senior analyst at VDC, who tracks the PoE and Power Management markets.
Akros Silicon has also successfully completed testing the interoperability of the new AS1135 PD Controller with Microsemi’s recently released PD64001 PSE Power Manager, in accordance with the IEEE 802.3at-Draft2.0 standard – an important milestone for the industry, as it allows customers to effortlessly implement both ends of the PoE link (both PSE and PD).
EN-Genius Says…
The enhanced Power-over-Ethernet standard, sometimes being called PoE+ has been a long time coming. The committee first sat in 2005 and although drafts of the new standard have been released, the work has been slow in its finalization. In the meantime a couple of companies – notably Cisco, who are heavily represented on the committee – have released their own enhanced standards to satisfy current customer needs. Cisco has promised to conform to the new standard when it is signed off.
The original PoE standard, IEEE P802.3af, allowed for up to 48 V of phantom power to be applied to one pair of either a Cat 3 or Cat 5 cable. With a limitation of 400 mA the maximum power that could be delivered to a cable was 15.4 W or, effectively, 12.95 W after 100 m of cable losses. The dc-dc conversion of the voltage at the powered device (PD) caused another 10 – 20 % loss.
The enhanced standard IEEE P802.3at had the objective of providing at least 30 W at the PD, although the result has been to fall just slightly shy of that number. In theoretical terms it has been accepted by ISO/IEC that Cat 5 (which uses 24 AWG) cable can be safely rated for 360 mA, per pair, at 50 V. The committee has also verified the safety of the connectors and with all four pairs in use for phantom power the maximum power would be 50 x 0.36 x 4 = 72 W, say 59 W at 100 m. 30 W is certainly within a safe margin. 802.3at systems must also be back-compatible with 802.3af ones but Cat 3 cable is no longer usable.
Akros released the AS1135 on March 17, 2008, the day before the IEEE P802.3at DTE Power Enhancements Task Force met again in Orlando, FL. The new standard uses the Class 4 signature that was left as “reserved” in the original standard and the Type 2 PSE controller also sends a second pulse to tell the PD that it is PoE+ rated. An AT Detect pin is provided on the Akros part to indicate that has happened.
The AS1135 includes an input surge protection, the new signature system, thermal and current limits, undervoltage lockout, control to switch to a local power source, and the dc-dc controller. The current limit can be set to a little higher than the standard (at 800 mA) while the local voltage can range from 10 V to about 57 V. The dc-dc converter can be set up with external components as a flyback, forward or buck configuration. The switching frequency can be exterally set between 100 kHz and 500 kHz. The MOSFET, they say, will have a maximum Rds(on) of 0.8 Ω.
Efficiencies, etc., are unknown at this stage as the company has a registration requirement for data sheets.
Will the production of the AS1135 be premature with a non-signed-off standard? Unlikely. The remaining hiccups of the standard seem to be in the areas of bridge power delivery, and dotting “i”s and crossing “t”s so Akros is probably very safe in going ahead. What do they have going for them? Their surge protection is, presuambly a derivative of their EMI suppression and will stand them in good stead in the marketplace. They are also pricing themselves in a very positive position. As with all start-ups their name recognition will be their main, initial, barrier in getting a share of what is going to be a huge market with access points and web/security cameras being at the top of a very long list of the expanded product range that can now be supported. Will they make it? I think they will.
The AS1135 is in production in Pb-free QFN-20 and is priced at $1.66 in 1-k piece lots.
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