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AM2432: IBIS Model

Mari Tsunoda
Expert 5726 points

Part Number: AM2432
Other Parts Discussed in Thread: AM2431, DRA821U

Hi Team,

My customer has questions regarding the IBIS model.

  1. Looking into IBIS model(sprm730.ibs), there are two variations "LVCMOS_H" and "LVCMOS_V" for LVCMOS model. what's the difference between them? For example, PRG0_PRU1 GPO9 pin attaches LVCMOS_H model, but PRG1_PRU0_GPO0 attaches LVCMOS_V model in the sprm730.ibs.
    On AM2431 datasheet, Table 6-1. Pin Attributes (ALV, ALX Packages) (continued), I compared the details of PRG0_PRU1_GPO9 and PRG1_PRU0_GPO0. it seems that the difference is only Power domain(VDDSHV1 or VDDSHV2). Are there any other factors contributing to the difference?

  2. Looking into IBIS model(sprm730.ibs), it seems that there are six variatons for LVCMOS_H (1.8V/3.3V x Nom/slow/Fast). Which one should I use for the simulation?

    |********** LVCMOS
    [Model Selector] LVCMOS_H
    lvcmos1_nom_1p8_h PRWDWUWSWEWCDGLVCMOS_H@_Nom_1p8_comment
    lvcmos1_nom_3p3_h PRWDWUWSWEWCDGLVCMOS_H@_Nom_3p3_comment
    lvcmos1_slow_1p8_h PRWDWUWSWEWCDGLVCMOS_H@_Slow_1p8_comment
    lvcmos1_slow_3p3_h PRWDWUWSWEWCDGLVCMOS_H@_Slow_3p3_comment
    lvcmos1_fast_1p8_h PRWDWUWSWEWCDGLVCMOS_H@_Fast_1p8_comment
    lvcmos1_fast_3p3_h PRWDWUWSWEWCDGLVCMOS_H@_Fast_3p3_comment

    I found a related post on TI E2E.
    e2e.ti.com/.../dra821u-does-the-ibis-model-work-with-the-drv_str-setting
    DRA821U: Does the ibis model work with the DRV_STR setting? - Processors forum - Processors - TI E2E support forums

    It mentions about another device, but it says I can use the model which set on the DRV_STR bit on padconfig register.
    In the answer of another Q&A(no.86), We should set DRV_STR as 00b. Does that mean we use Nom model for the simulation?
    I expect that We can choose Slow model(set DRV_STR the value of "Slow" driver-strength). because there are models for Slow-driver. Considering signal rate and PWB design, I'd like to use slow driver for output pin.

Best regards,

Mari Tsunoda

  • +1
    TI__Expert 7435 points

    Hello Mari,

    There is an updated IBIS model for the AM243x that has updated values and this is the version that should be used for simulations. Please make sure that sprm730b.ibs (https://www.ti.com/lit/zip/sprm730) is being used for simulations. 

    1. Looking into IBIS model(sprm730.ibs), there are two variations "LVCMOS_H" and "LVCMOS_V" for LVCMOS model. what's the difference between them?

    The suffixes, _H and _V, refer to the orientation of the IO where _H is a horizontal orientation and _V is a vertical orientation. 

            2. Looking into IBIS model(sprm730.ibs), it seems that there are six variations for LVCMOS_H (1.8V/3.3V x Nom/slow/Fast). Which one should I use for the simulation?

    For the 1.8V vs 3.3V model, it depends on whether you plan to supply the IO supply VDDSHV<n> for IO group <n> with 1.8V or 3.3V. The datasheet lists each ball number's POWER. For example, The AM243x LaunchPad connects IO supply VDDSHV[0-4] to 3.3V supply and therefore all balls in the VDDSHV[0-4] power domain should be 3.3V models. 

    The DRV_STR bits of the padconfig registers are 00b on reset  which correlates to the nom model. If the application requires a "Slow" driver-strength for the pin then DRV_STR (bits 19-20) should be set to 10b. It is good practice to simulate across all 3 process corners (nom/fast/slow) in order to get a complete idea of performance across process variation. Here is an example of a PADCONFIG register:

    Regards,

    Erik