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TMS320C6747: 456Mhz version of device with 400Mhz CPU Freq

Naoki Kawada
Guru 19890 points
Part Number: TMS320C6747
Other Parts Discussed in Thread: D810K013DZKB400, D810K013DZKB456, DA8XX

Hi,

The title shows that the part number is C6747, but in fact, DA810. 

456Mhz part of DA810, running at 456Mhz, requires 1.3V (nominal) for CVDD, but does 456Mhz part, running at 400Mhz, require the same voltage ? I`m wondering if 1.2V might be enough to meet its operation condition. My customer is using 400Mhz part in their product, but because of its supply shortage, they are considering replacing 400Mhz part with 456Mhz one *without* HW/SW changes. I saw some specific AC timing parameters only for 456Mhz part in the datasheet. For example, EMIFB timing is different from 400Mhz part and 456Mhz one. Is AC timing of 400Mhz part applicable for 456Mhz part running 400Mhz ?

Best Regards,
Naoki

  • 0
    TI__Guru**** 161600 points
    Hi Naoki,

    The title shows that the part number is C6747, but in fact, DA810.

    456Mhz part of DA810, running at 456Mhz, requires 1.3V (nominal) for CVDD, but does 456Mhz part, running at 400Mhz, require the same voltage ?


    Could you specify which device is this exactly? You can refer to device nomenclature Figure 7-1. Device Nomenclature, you can have 300 MHz (for Revision A), 375 MHz (for Revision B) and 456 MHz (for Revision B) devices.

    For the TMS320C6747 see Table 3-1. Characteristics of the C6745/C6747 Processor. The processor works at 456MHz (1.3V CVDD).

    Best Regards,
    Yordan
  • 0 in reply to Yordan Kovachev
    Guru 19890 points

    As I mentioned, I`m actually asking about DA810 part. Because I couldn`t specify the part number on this e2e title (DA810 is not catalog part, so it may not be listed in part number candidates), I just temporally used C6747.

    So the  exact part numbers :

    - Current device : D810K013DZKB400
    - Replacement device : D810K013DZKB456

    Please note D810K013DZKB400 is running with allowed frequency, say 400Mhz, by configuring internal PLL registers controlled by their software appropriately. They suppose to keep the PLL configurations on D810K013DZKB456, so D810K013DZKB456 is expected to run at 400Mhz, rather than its max speed :456Mhz. Also, SDRAM clock speed won`t be changed. In this case, is it okay to use 1.2V (not 1.3V) for CVDD with D810K013DZKB456  ? If yes, can we refer 1.2V specific AC Timings with D810K013DZKB456 ? For example, the following red square in datasheet:

    Best Regards,
    Naoki

  • 0 in reply to Naoki Kawada
    Guru 19890 points
    Any update on this ? I`m waiting for your reply.

    Best Regards,
    Naoki
  • 0 in reply to Naoki Kawada
    TI__Guru** 114410 points
    Naoki-san,

    Thanks for bringing this to our attention. The official datasheet recommendation for 400 MHz seems to be fuzzy. In most places it indicates that 375 MHz is the max for 1.2V setting and 456MHz would require to use CVDD (1.3) except for the foot note provided under EMIFB Electrical and timing table.

    I will check on this with the design and systems team and get back to you ASAP . Appreciate your patience on this issue.

    Regards,
    Rahul
  • 0 in reply to Rahul Prabhu
    TI__Guru* 78415 points
    The lead engineer who owns this datasheet is out of office this week. We will try to provide some guidance on this early next week. The responses will be specifically for D810x family and will not be applicable to c6747
  • 0 in reply to Mukul Bhatnagar
    Guru 19890 points
    Did you get any response form the owner ?

    Best Regards,
    Naoki
  • 0 in reply to Naoki Kawada
    TI__Guru** 114410 points
    I got a confirmation from the lead engineer that 400 Mhz part also uses 1.2 V core voltage settings on DA8x parts.

    Regards,
    Rahul
  • 0 in reply to Rahul Prabhu
    Guru 19890 points

    Rahul Prabhu said:
    I got a confirmation from the lead engineer that 400 Mhz part also uses 1.2 V core voltage settings on DA8x parts.

    Just a clarification. You wanted to say, "I got a confirmation from the lead engineer that 456 Mhz part also uses 1.2 V core voltage settings on DA8x parts.", right ?
    This means we can use 456Mhz part with 1.2V CVDD supply voltage and in this case, we can regard it as 400Mhz part with 1.2V CVDD supply voltage and the same AC timing with 400Mhz part is expected. 

    Best Regards,
    Naoki

  • 0 in reply to Naoki Kawada
    TI__Intellectual 2350 points

    Hi Kawada-san, let's move to email now.  We should avoid DA8xx talk on this forum.  I have the beginning of an answer.