The Challenges of PoE+

Focus:

The IEEE 802.3at standard for high-power power over Ethernet (also know as PoE+) will permit PoE powered devices (PDs) to consume up 25.5 W. That's almost double the power (12.95 W) allowed in the original PoE standard IEEE 802.3af. However, to make the new standard's higher power limit available to PDs, manufacturers of networking equipment will need to upgrade their power sourcing equipment (PSE) designs. Upgrading a PSE design to comply with the 'AT standard entails changes in Ethernet magnetics,a change to new PSE controller ICs, larger MOSFETs (in some cases), a larger power supply, and various other components that must be rated to handle the higher current level. In addition, the PSE's pc-board design must be modified to handle higher current. PSE integrated connector modules, which combine PSE circuitry and Ethernet magnetic in a ganged connector assembly, eliminate a number of these upgrade design challenges. These modules will become available with standard footprints and electrical specs thanks to a pending standard by the PoETech consortium. This article describes the advantages of using these PSE modules to implement 'AT-compliant PSE designs rather than doing discrete PSE designs.

What you’ll learn:

• How to simplify the design of high-power PoE equipment using PSE integrated connector modules
• How to understand the impact of IEEE-802.3at standard for high-power PoE on PSE design

Notes:

Article is found on pages 25-27 of June 2009 issue in the Power Systems Design archive. To access the archive, you must log in as a member of the PSD Community at www.powersystemsdesign.com/signup.

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Author & Publication:

Alison Steer, Product Marketing Manager, Mixed Signal Products for Linear Technology Corp., Milpitas, CA, Power Systems Design Europe, Jun 01 2009

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