Suggested Remedy for Comment #34 rev 001

IEEE802.3at Task ForceVport ad hocDraft 1.0Suggested Remedy for comment #34Rev 001Jan 2008Yair DarshanMicrosemi Corporationwww.microsemi.comSuggested Remedy for comment #34 , Yair Darshan, Jan 2008 Page 1Comment #3433.3.5.2, Page 60, Line 47, TR, Draft 1.0Comment:The equation and instruction for measuring PPort seem unnecessary. The power limit applies regardless of the PE voltage and cable impedance.The sudden appearance of a resistive approximation of the cable plantreally adds nothing for the reader. Stating that the power limit applies over the specified input voltage range is simply redundant. Telling the reader that power equals voltage times current is a bit patronizing.Suggested Remedy:Replace 33.3.5.2 with the following:The specification for PPort in Table 33-12 (item 2) shall apply for the inputpower averaged using any sliding window with 1s width. www.microsemi.comSuggested Remedy for comment #34 , Yair Darshan, Jan 2008 Page 2Adhoc DiscussionBackground from 802.3afThe PD is not just a resistor it is a system which present a load with negative impedance, connected to a limitedpowe source through non zero impedance connection. Such system may present the following problems:a) Startup oscillations (low frequency) which was solved in the standard by defining the UVLO functions through Von andVoff parameters in Table 33-5. (See reference 1)b) High frequency oscillations which can be solved by meeting the ...