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TDA4VM-Q1: DDRSS virtual eye diagram margin

yutai li
Intellectual 625 points

Part Number: TDA4VM-Q1

Hi  TI Support Team

How to check the virtual eye diagram margin for green area region and purple area region. 

e.g.  Purple area means DQS read/write trigger DQ signal . Is it correct ? 

       If the purple area in green area => that means DQ can successful read/write by TDA4/DDR. Is it correct ? 

Thanks

Yutai

  • 0
    TI__Mastermind 43580 points

    Hi,

    The purple represents the approximate trained location (in other words, where the data would be sampled / latched by the receiver). Ideally, the purple should be relatively centered within the green cells.  

    Best regards,
    Kevin

  • 0 in reply to Kevin S
    Intellectual 625 points

    Hi Kevin

    In my customer board, We use JTAG tools check virtual eye diagrams.
    For read case: the purple area not always in centered green area.
    We already followed your (local TI FAE) suggestion change the training pattern from 7 to 6. 

    So my query is that how to optimize the DQS to  

    DQ delay value in TDA4 register setting? 
    e.g. Add delays for DQS ?

    By the ways:
    I think you already get our project some test report  and virtual eye diagram from TI FAE team.  Can you please double check it. 

    Thanks

    Yutai

  • 0 in reply to yutai li
    TI__Mastermind 43580 points

    Hi Yutai,

    Changing the write DQ training  pattern from 7 to 6 is unrelated to the READ eye, and not expected to have a significant impact on the WRITE eye. The main reason we have suggested changing the pattern from 7 to 6 is to work-around a write DQ training issue that has recently surfaced on some systems.

    We will review the data that was sent from the meeting actions and follow-up through email.

    Thanks,
    Kevin

  • +1 in reply to Kevin S
    Intellectual 625 points

    Thanks, We have do more test case. Let us discuss in meeting.