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[802.3af] Power Classification

Hi, I need a little help understanding exactly how the power classification
method works. As I understand it, this is performed using the measured
current or measured voltage method. How does the Powered device give the
correct signature for its class? as an example, what circuit would I use on
the powered device for the PSE to detect it as a Class 1 device?

Secondly is this classification procedure performed only at power up?
for example if a powered device went into standby mode, thus reducing power
consumption, would the PSE attempt to reclassify the device based on it's
new current usage, or would it simply disconnect the power to the device?

From the draft I have (3.0), it's difficult to answer these questions, does
the new draft (3.2) have a better explanation?

Thanks in advance for your time.

Best Regards,

Malcolm Humphrey BEng (Hons)
Hardware Development Manager
NetEngines Ltd
146 Walnut Tree Close
Guildford, Surrey

direct: +44 (0)7044 021234
office: +44 (0)8707 107010
Fax:    +44 (0)8707 107020
E-mail: malcolm.humphrey@xxxxxxxxxxxxxxxx