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AM37xx IBIS Model file

Hiroshi Kimizuka
Expert 4400 points
Hi, My customer is facing to the error at the SI with AM37xx IBIS Model(IBIS ver 4.1, File rev 1.0) as below; 1) Package description: In the component description of the AM37xxCUS IBIS file(IBIS ver 4.1, File rev 1.0), there is a "Package" description with the minus min value; L_pkg with "-3.65890e-011" and C_pkg with "-6.48373e-013". Are these minus values correct and recommended value ? I believe that the minus value of L and C component of package parameter does not make sense, and this makes a significant error in Signal Integrity simulation. 2) Model Selector: There are too many model names in the Pin field of the Component description of the AM37xxCUS IBIS file, for example, 4 model nemas(Selector7, 13, 14,16) are specified for DSS signals, and each Selector is refering to many Models(Selecor13 for DSS_DATA[0] (AC19) can refer to 36 Models). Customer would like to know which Model should be applied to the case for = 60MHz? 3) Model Selector for SRDC pins: Another customer is concerned about SDRC with DDR. This customer would like to know hich Model is corresponding to each pin model of SDRC. Can the only one buffer Model be configurable to the whole SRDC pins ? Otherwise, is it possible to configure any Model to each pin ? Thanks and Best Regards, KIMIZUKA
  • 0
    TI__Mastermind 43875 points

    Kimizuka,

    -ve values are fine in the mutual inductance matrix since these are values which are mathematical models of the interaction of the signal to signal and not simply an in line inductance.

    Regarding the model selectors each pin only has one model selector. Each model selector describes the possible options available for that specific pin. The option selected depends on many factors such as the power supply tolerance of the customer PCB, selected mode of operation, drive strength selected etc... and will depend on the specific customer configuration. Please have a look at this forum question which also describes a little about the structure of IBIS http://e2e.ti.com/support/dsp/davinci_digital_media_processors/int-dm81x/f/518/p/104230/366767.aspx#366767

    BR,

    Steve

  • 0 in reply to Steve Clynes
    TI__Expert 4400 points

    Hi Steve,

    Thank you for your reply.

    OK, these minus values in the L_pkg and C_pkg are no problem. 

    However, customers are facing to the significant error in their SI simulation, could you advise me how to suppress the error in the SI with minus value? 

    Regarding the model selectors, it is possible for customers to select the model selector by pin depending on the their option.

    In order to choose the most suitable model selector, is there any guidelines or whatever helps them ?

    For example, they seem to see the difference between SC00LB00/SC00LB01/SC01LB10/SC01LB11/SC10LB10/SC10LB11.

     Thanks and Best Regards,

    KIMIZUKA

     

  • 0 in reply to Hiroshi Kimizuka
    TI__Mastermind 43875 points

    Kimizuka,

    I can't comment on the simulations but I have passed the question on to someone who can hopefully help.

    Regarding the model selections usually the user can select through software configuration exactly what the characteristics of the IO are, so the intent here is that each selector could be simulated then the model which gives the best results is the one that is then programmed on the processor.

    In the case you mention I believe that SC is the slew rte control and B is the buffer strength. The customer should refer to the device data sheet to determine how these SC/B terms relate to device configuration options.

    BR,

    Steve

  • 0 in reply to Steve Clynes
    TI__Mastermind 43875 points

    Kimizuka,

    I am a little confused?

    You mention...

    OK, these minus values in the L_pkg and C_pkg are no problem. 

    However, customers are facing to the significant error in their SI simulation, could you advise me how to suppress the error in the SI with minus value?

    First you mention there is no problem, but then say there are errors?

    As a test can the customer remove the package section from the model (lines 40 thru 45) to force the simulation tool to use the fully qualified mutual RLC matrix, which is OK to have mutual -ve values)?

    What simulator is your customer using?

    BR,

    Steve