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Re: [802.3_4PPOE] IEEE802.3bt End to End Channel Pair to Pair Resistance Unbalance - Proposed PSE and PI Speciication



Hi Jeff,

Some first comments:

 

Slide 4:

 

2nd bullet. Not clear why you mention SELV etc.?

 

5th bullet.

- Try to specify unbalance with absolute values so positive or negative voltage differences is not important.

-The fact that lower or higher V2 that can compensate higher/lower R2 is true however the test should address it inherently to simplify the test

-To cover both points try to define mathematical desired _expression_ and then design what the test setup need to be to test it. For example; I would start to play with the following: RUNB=dV/dI. What is need to be done so for a given requirement of worst case RUNB limit, the dV will not exceed  di or equivalent method.

-I would try to replace the V1 with some fixed resistive load that represents the current during normal operation so P2PRUNB between ANY two pairs can be extracted . (P2PRUNB is defined between any two pairs).

 

6 bullet:

-No need to test pair unbalance. No value added. Its effect on P2PRUNB is negligible.

 

Slide 5:

 

Similar comments.

 

Regards.

 

Yair

 

 

 

From: Jeff Heath [mailto:jheath@xxxxxxxxxx]
Sent: Tuesday, May 06, 2014 12:11 AM
To: STDS-802-3-4PPOE@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_4PPOE] IEEE802.3bt End to End Channel Pair to Pair Resistance Unbalance - Proposed PSE and PI Speciication

 

All,

 

Here is my proposed way to create balance specifications at the PSE and PI.  I welcome any comments.

 

Regards,

 

Jeff Heath
Design Center Manager

Description: Linear Technology Corporation

 

 

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