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DS90UB954-Q1: About Margin Analysis

Masanori Okano
Prodigy 230 points
Part Number: DS90UB954-Q1
Other Parts Discussed in Thread: ALP, USB2ANY

Hi Team,

Please tell me about the margin analysis of FPD-LINK III.

Question 1.
Am I correct in my understanding of margin analysis using USB2ANY and ALP as follows?
(1) It is not checking voltage levels.
　　It is different from EYE aperture observed with an oscilloscope.

(2) It is checking the lock status and various errors for good or bad.
　　I referred to the following text written in the application note SNLA301.

www.ti.com/.../snla301.pdf

Excerpt.
4 Margin Analysis Program (MAP) Using Manual Strobe Control
These diagrams track lock status, parity errors, forward channel CRC errors, forward channel sequencing errors, and forward channel encoding errors (0 x4D[5:2] and 0x4E[5]) over all EQ settings and strobe positions using the smaller base delay.

Question 2
What forward channels are used when performing margin analysis?
Will I use the forward channel of the SerDes system I designed to perform margin analysis using different EQ levels and strobe positions?
(My system is connected to a 933 and a 954)

Best Regards,

  • 0
    TI__Guru 56345 points

    Hi Okano-san, 

    Masanori Okano said:

    Question 1.
    Am I correct in my understanding of margin analysis using USB2ANY and ALP as follows?
    (1) It is not checking voltage levels.
    　　It is different from EYE aperture observed with an oscilloscope.

    (2) It is checking the lock status and various errors for good or bad.
    　　I referred to the following text written in the application note SNLA301.

    Yes, this is correct. This is not a discrete eye measurement, but instead a shmoo plot comparing the EQ and strobe location and red/green status based on error/lock loss statuses. 

    Masanori Okano said:
    uestion 2
    What forward channels are used when performing margin analysis?
    Will I use the forward channel of the SerDes system I designed to perform margin analysis using different EQ levels and strobe positions?
    (My system is connected to a 933 and a 954)

    Yes, it is best to analyze the system with MAP tool in "mission mode", meaning you are using the target PCLK/line rate to then evaluate the link margin and EQ/strobe location results. 

    Please let me know if there are additional questions. 

    Regards, 

    Logan