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Which C6748?

DanB57495
Expert 1340 points

Hello,

We have been using the Logic PD L138 EVM kit to port/develop some code using the C6748 SOM that Logic had at the time which had an experimental TMX320C6748ZCE, revision-1, 300MHz. CPU. We are looking to create some hardware now and need to zero-in on the right model.

We are not a high-volume user so we need to make sure we choose a model that will be readily available from most distributors.

Questions:

1) So far it seems the ZWT (0.8mm Ball Pitch) version is somewhat more available than the ZCE (0.65mm). Is ZWT more likely to be the main device type? So long as form and function are the same as the ZCE this is fine and is easier to layout.

2) I see that the 'B' (revision 2) seems available. Should I assume that 'A' will no longer be made?

3) In the same thought I see that speed grade 3 for revision 2 is 375MHz rather than 300MHz and that there is a speed grade 4 (456MHz). Assuming that the power increase is mostly proportional with the clock speed, we may be interested in the 456MHz if the design from the original Logic PD EVM boards can still be used as a reference?

4) It seems that the speed grade 3 (375MHz for rev 2) is somewhat available while grade 4 (456MHz) does not seem available . Should I expect that grade 3 will be the primary device and grade 4 a special? Or will grade 4 likely replace grade 3?

Thank you on behalf your small-to-medium-volume user!

Dan.

  • 0
    TI__Guru 62975 points

    DanB said:

    1) So far it seems the ZWT (0.8mm Ball Pitch) version is somewhat more available than the ZCE (0.65mm). Is ZWT more likely to be the main device type? So long as form and function are the same as the ZCE this is fine and is easier to layout.

    Can you clarify what you mean by more reliable?  The same silicon die stock is used for both packages so there should be no underlying device reliability differences.  If you are referring to general routing and assembly issues related to different ball pitches, I would defer to your own experience.

    DanB said:

    2) I see that the 'B' (revision 2) seems available. Should I assume that 'A' will no longer be made?

    Yes, older revs are discontinued as newer revs are ramped up.

    DanB said:

    3) In the same thought I see that speed grade 3 for revision 2 is 375MHz rather than 300MHz and that there is a speed grade 4 (456MHz). Assuming that the power increase is mostly proportional with the clock speed, we may be interested in the 456MHz if the design from the original Logic PD EVM boards can still be used as a reference?

    We have not had significant reports of problems when overclocking the EVMs and SOMs to 375MHz / 456MHz at room temperature.  Please note that the 456MHz operating point requires an increase in core voltage.  You can see the estimated power difference using the spreadsheet tool here: http://processors.wiki.ti.com/index.php/OMAP-L138_Power_Consumption_Summary

    DanB said:

    4) It seems that the speed grade 3 (375MHz for rev 2) is somewhat available while grade 4 (456MHz) does not seem available . Should I expect that grade 3 will be the primary device and grade 4 a special? Or will grade 4 likely replace grade 3?

    The 375MHz speed grade will be the primary device offering.

  • 0 in reply to tlee
    Expert 1340 points

    Hello tlee,

    For #1: I was saying that the ZWT seems to be more AVAILABLE (not reliable). My assesment of availability was based on a search on FindChips.com. I am trying to find out if the ZWT will end up becoming the main offering while ZCE might be harder to get?

    For #2: Thanks.

    For #3 and #4: Thanks. Based on that reply I think we will stick with the 375MHz standard offering.

    Just waiting for your thoughts on #1.

     

    Dan.

  • 0 in reply to DanB57495
    TI__Guru 62975 points

    DanB said:

    For #1: I was saying that the ZWT seems to be more AVAILABLE (not reliable). My assesment of availability was based on a search on FindChips.com. I am trying to find out if the ZWT will end up becoming the main offering while ZCE might be harder to get?

    oops.  Not sure how I misread that.  I think that the target inventory of package offerings between ZWT and ZCE is meant to be equal.  There are a significant number of customers for both packages so I don't foresee one package being phased out in favor of another.  I would recommend using the package that better fits your application.  In case both meet your package / size requirements, I've heard that ZWT is easier to route because of the larger pitch.

  • 0 in reply to tlee
    Expert 1340 points

    OK.

    Sounds good.

    Thanks for your help.

    Regarding routing: It is sometimes harder to find PCB fabrication houses that can handle the smaller traces, vias , and spacing needed for smaller footrpint devices, so in this way ZWT would be a better choice.

    Thanks again.

    Dan.