Akros Silicon's PD controller targets PoE Plus
April 3, 2008 -- The provider of Power-over-Ethernet (PoE) mixed-signal ICs recently released its AS1135 powered device (PD) controller, which implements the 2-Event Physical Layer Classification functionality of the IEEE 802.3at PoE Plus standard.
April 3, 2008 -- Akros Silicon Inc., a provider of Power-over-Ethernet (PoE) mixed-signal ICs, recently released its AS1135 powered device (PD) controller, which implements the 2-Event Physical Layer Classification functionality of the IEEE 802.3at PoE Plus standard.
The PoE Plus standard raises the maximum available PD input power to 30W from the previously specified level of 13W in the existing 802.3af standard. The 30W power level opens up a range of new applications for PoE, including IP security cameras with power, tilt and zoom (PTZ) capability, 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, according to Akros Silicon.
"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," offers Brian Greenberg, senior analyst at VDC, a technology research firm who tracks the PoE and power management markets.
The AS1135 controller supports a variety of new features in the same 5x5 20-pin QFN package as the company's AS1100 family. The part provides "AT Detect" functionality on a logic output pin, indicating successful PoE connection to Type 2 PSE. This hardware feature can be used by the system micro-controller to self-configure the networked appliance based on the power delivery capability of the network. The AS1135 is also capable of operating with local power input as low as 10V.
"There are many instances where it is beneficial to provide Ethernet appliances that can operate from the power supplied by either the PoE line or a local power source," comments Amit Gattani, director of marketing at Akros Silicon. "For instance, manufacturers of IP cameras may want to provide the local power option to allow their product to be used in a network that has not yet been upgraded to PoE. This feature allows system designers to benefit from the use of commonly available, low-cost 12V power adapters for auxiliary power."
Another new feature is the capability to externally set the switching frequency of the integrated DC-DC controller in the 100kHz - 500kHz range. This gives designers flexibility to optimize the system for parameters like EMI, power consumption and component sizes. Lower switching frequencies can be beneficial in controlling EMI and improving no-load efficiency. Designers may also use higher switching frequencies to reduce the size of components used in the power converter output stage. These features are additions to standard features found in the AS1100 product family like integrated surge protection and low emissions DC-DC controller, to enable EMC ready system designs.
Akros offers reference designs and evaluation boards to help evaluate the performance of the AS1135. The AS1135 is available in the 20-pin 5x5 QFN, with a Reduction of Hazardous Substance (RoHS) compliant package. The device is priced at $1.66 for 1kU quantity.
Akros Silicon has also completed testing the interoperability of the AS1135 PD controller with Microsemi's recently released PD64001 PSE Power Manager, in accordance with the IEEE 802.3at standard, enabling customers to implement both ends of the PoE link (both PSE and PD).