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DP83TC811S-Q1: Question on Low Pass Filter

Mitchell
Expert 4915 points
Part Number: DP83TC811S-Q1

Hi Team,

My customer is in the process of designing the DP83TC811S-Q1 into their system and they have a question on the Low-Pass Filter that's required to pass emmissions and immunity testing. 

When they model this in a circuit simulation program, this circuit seems to violate the Return Loss specification for 100base-T1. Is this expected? 

I've confirmed that they are adhering to Figure 141 in the datasheet and the recommended are being used. They are using S-parameter models of the actual components meeting the specifications given in the datasheet.

As a second question, the datasheet refers us to the SNLA293 application note, but we are unable to find this document online. Can you please let me know where to find this?

Thanks,
Mitchell

components

  • 0
    TI__Mastermind 23675 points

    Hi Mitchell,

    The app note is provided upon request only.

    Please send me an email. 

    As for the RL measurements, it is probably because they are modeling the line driver of the 811 as a perfect 100 ohm termination.

    This is never the case because there are going to be some non-linear behavior of any driver used.

    When doing PMA validation at UNH IOL test house, we pass RL and LMC.