DP83848Q-Q1: PMD input pair requirements

Hello,

I am confirming the requirements you listed down. I will get back to you on 3rd August.

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Regards,

Vikram

Hello Vikram,

Thank you for supporting me on this ticket.  Would you please update the status?

Best Regards,

Yoshikazu Kawasaki

Hello Yoshikazu Kawasaki,

Sorry to keep you waiting for so long. Here is what you were looking for :

1. If the PMD input is greater than 1000mV then we guarantee that signal detect will be high.

2. If the PMD input is lesser than 200mV then we guarantee that signal detect will be low.

This hysterisis is provisioned by standard : ANSI FDDI TP-PMD and IEEE for reliable detection of signal.

Receiver of 848 is as per 100BFX IEEE requirements.

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Regards,

Vikram

Hello Vikram,

Thank you for your reply.  Please let me confirm a little bit more.

- I understand the PMD input between 200mV and 1000mV violates the standard of ANSI FDDI TP-PMD, but would you please tell me what would be returned from DP83848Q-Q1 if PMD is between 200mV and 1000mV?  Will it remain the previous state of CRS, CRS=low if the amplitude increases from =<200mV and CRS=high if it decreases from >1000mV?  Or CRS=high only when PMD>=1000mV which gives CRS=low even when 200mV<PMD<1000mV?  Or CRS=low only when PMD=<200mV which gives CRS=high even when 200mV<PMD<1000mV?

- Is the amplitude the only condition to detect PMD input?  Or will it require others like rise/fall time or something?

Best Regards,

Yoshikazu Kawasaki

Hello Vikram,

Please let me add one more.  So the questions are summarized as below.

1.I understand the PMD input between 200mV and 1000mV violates the standard of ANSI FDDI TP-PMD, but would you please tell me what would be returned from DP83848Q-Q1if PMD is between 200mV and 1000mV?  Will it remain the previous state of CRS, CRS=low if the amplitude increases from =<200mV and CRS=high if it decreases from >1000mV?  Or CRS=high only when PMD>=1000mV which gives CRS=low even when 200mV<PMD<1000mV?  Or CRS=low only when PMD=<200mV which gives CRS=high even when 200mV<PMD<1000mV?

2. Is the amplitude the only condition to detect PMD input?  Or will it require others like rise/fall time or something?

3. Would you please also tell me the conditions of RX_DV=H?

Best Regards,

Yoshikazu Kawasaki

Hello Yoshikazu Kawasaki,

PMD value between 200mV and 1000mV is not deterministic and output can be either 1 or 0. Hence system must ensure that signal value is > 1000mV for detection of valid signal and less than 200mV for detection of "no signal".

There are many electrical specs defined in ANSI FDDI TP-PMD and for that we request you to refer to the standard document. 848 is compliant to the standard.

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Regards,

Vikram 

Hello Vikram,

Thank you for your support.  Please let me confirm one more thing.  Would you please tell me exactly which one of A or B (or others) the PMD input pair needs to be?

DP83848-Q1_PMD_Input_Check.pdf

Best Regards,

Yoshikazu Kawasaki

Hello Yoshikazu Kawasaki,

Is the plotted signal V(RD+) - V(RD-) or only V(RD+)? Basically if you are plotting V(RD+) - V(RD-) on the scope then difference between highest and lowest point of this waveform should be greater than 1000mV.

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Regards,

Vikram