PoE Features Tackle High-Power and Other Design Challenges

Mar 28, 2007 2:55 PM

This month at the Power Electronics Technology website, a special section on power over Ethernet (PoE) presents a series of articles addressing different aspects of PoE design. The four articles in this section are intended to aid designers in optimizing or simplifying their power sourcing equipment (PSE) and powered device (PD) implementations.

In “Emerging Standard Drives High-Power PoE Design,” Daniel Feldman, Product Line Manager at Microsemi outlines the requirements of the emerging IEEE802.3at standard, which will increase the power available to the PD from 12.95 W to 59 W. Feldman discusses the impact of these requirements on issues such as cable selection, power classification, power allocation, and compatibility with IEEE802.3af.

Another article, “Optimize Flyback Magnetics to Empower the PD” by John Gallagher of Pulse Engineering explains how to design the flyback transformer when implementing a flyback power converter in the PD. As Gallagher explains, the continuous mode flyback topology is particulary well suited to PDs because it represents the simplest and lowest cost isolated topology at the PD’s 13-W power level.

As in all power applications, reliability is a concern in PoE. In “Surge Protection Brings Big Benefits to PoE Systems” Jean Picard of Texas Instruments discusses how the IEC 61000-4 transient immunity standards apply in PoE. Picard discusses the test methods associated with these standards, and provides guidelines and design solutions for implementing circuit protection.

Naturally, some unique PoE designs are made possible by recent component developments. In the feature, “Single-Port PSEs Put Power in More Places” Dilian Reyes of Linear Technology describes the design of a single-port PSE controller that may find application in a PSE wall adapter, a power forwarding unit, or in any product in which a single powered port is needed.

While these design articles address existing and emerging design challenges in PoE, an article from the March issue of Power Electronics Technology describes some of the recent improvements in PoE power management ICs. “PoE Chips Reach For Higher Power and New Features” describes recent advances in PSE controllers, which will help designers develop high-power in their PoE systems, while also achieving higher integration and more autonomous operation.