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AM4378: Clarification on sprm636a ibis model

Gunasekar T
Prodigy 110 points
Part Number: AM4378

Dear Team,

Am doing the SI analysis of DDR3L of AM4378 processor and am using the sprm636a ibis model. I need the below clarification on model selection for DDR3L simulation.

The voltage level am using is 1.35V.

1. Which model I need to select for DQS- ODT enabled and DQS- ODT disable

2. Which model I need to select for DQS#- ODT enabled and DQS#- ODT disable

3. Which model I need to select for DQ- ODT enabled and DQ- ODT disable

4. Which model I need to select for DQM- ODT enabled and DQM- ODT disable

Please suggest the model selection since am tried but error is coming.

Thanks,

Gunasekar.T

  • 0
    TI__Guru 72860 points

    Here's an example for DQS.  I reference line numbers in the ibis file.  You should be able to extend this example to the other signals

    1. First determine which selector the signal is in.  For DDRx_DQS, all these signals are in Selector 11

    2. Find the section for DQS signals (line 371), then scroll down to Selector 11 (line 906)

    3. The first parameter is 3-state (output) or INPUT.  Since you are asking about ODT enabled, you would scroll down to all of the INPUT selections to choose the model you would use for read

    4. Next, choose the appropriate voltage 1.35V, the appropriate ones are lines 1149-1192

    5.  Now choose the ODT setting you are using.  The AM437x EMIF Tool spreadsheet chooses Full Termination

    6.  The next parameter corresponds to the driver setting.  I think you can choose any driver setting since this is for a read, but typically you would choose the driver setting for that IO.  In this case, the value from the EMIF Tool is 44ohm (9mA)

    7.  The next parameter is voltage tolerace.  Choose 5% here.

    8.  With these choices, we would choose Model 741 (line 1177).

    For the write model (where ODT is disabled), you would go through a similar approach, and choose the model with 3-STATE.  The write models have an extra parameter SR (slew rate), which the EMIF tool chooses 00b.  So for DQS during writes, you would choose model 307 (line 1053)

    Regards,

    James

  • 0 in reply to JJD
    Prodigy 110 points

    Hi James,

    Thanks for response.

    Am using hyperlynx tool for SI simulation

    1. As per your suggestion, Model-741(ODT enabled)  and Model-307(ODT-disable) is used for DQS signal.

    Similarly I tried for DQS# signal. it is in selector - 8, So I taken  Model-741 (ODT enabled) and Model- 563(ODT disable) but am getting "ODT model selection issue" as attached below snap. Please suggest for selection.  

    .

    2. Also suggest for Model for Non-ODT signals  (CLk,Add/cmd/ctrl signals) . In hyperlynx tool am not able to get the INPUT model for this. In default it is selected as selector-12 and in that for 1.35V, unable to get the INPUT model. .Thanks,

    Gunasekar.T

  • 0 in reply to Gunasekar T
    TI__Guru 72860 points

    I'm not familiar with Hyperlynx, you may have to pose the question to them if you getting an error.  

    As for #2, you shouldn't need an input model for clk/add/cmd/ctrl signals.  Those signals are output only, they are never inputs.

    Regards,

    James