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DP83TG720S-Q1: SGMII timing spec measurement

Chuqiang Wen
Expert 5865 points
Part Number: DP83TG720S-Q1

Hi Expert,

Could you please help me understand how to measure the SGMII timing spec--Trise and Tfall as shown below? 

For example, Trise is measured between 20% of Vod and 80% of Vod or not? And what is the Vod? 

The second question is, what is the impact if the rise and fall time is exceeded the spec? 

Thanks!

Ethan Wen

  • 0
    TI__Mastermind 19621 points

    Hi Ethan,

    Apologies for the long response time. I would need to reach out to the Validation team to answer this query. Thank you for your patience, I'll reach back to you with an update when I get one. Expect it to take 1-2 weeks.

    Regards,

    Alvaro

  • 0 in reply to Alvaro (Al-vuh-roe) Reyes
    TI__Mastermind 19621 points

    Hi Ethan,

    I received a response from the validation team:

    1. The SGMII SO_P and SO_N IOs are connected to oscilloscope through equal length SMA cables. Oscilloscope provides 50 ohm termination
    2. 101010…pattern is sent on SGMII. Register config to send 101010 pattern on SOP,SON is 0x42C<8>=1,0x425=0x02AA
    3. DPOJET application is invoked on oscilloscope. Rise-fall time measurement is added for 20%-80% range. The software calculates the VOD and accordingly sets the 20% to 80% thresholds to measure rise-fall time
    4. VOD is the output voltage, measured by scope
    5. What is the impact if the rise and fall time is exceeded the spec?
      1. What is not meeting the spec, our PHY or the receiving end? 

    Regards,

    Alvaro