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TMS320C6657: Power savinsg modes and lowest power estimate

Jeramie Bianchi
Expert 3315 points
Part Number: TMS320C6657

Customer is trying to estimate lowest power mode available when using the TMS320C6657.

The various TI documents all say something about looking at the device specific data manual:

Each Keystone I device incorporates different hibernation modes. For additional details, see the device specific

data manual and application reports. 

 

The datasheet, section 8.3.10, Power State Control Register talks about hibernation modes 1 & 2 and standby mode.  How can I be sure that our part number has those modes?  How can I tell what the power consumption is for these three modes?  There is no clue that I can see on the C6657 Power Consumption Summary Spreadsheet, or the App Report SPRABI5B, for how to represent these modes (simply).

 

I’m basically looking for this answer today, “what is the lowest power mode I can set my device in, and what is the power consumption in that mode.”  I realize it may not be that simple.

Thanks,

Jeramie

  • 0
    TI__Mastermind 46460 points

    Jeramie,

    This is not a simple answer.  The Power Consumption Model ( http://www.ti.com/lit/zip/sprm600 ) and the Power Consumption Summary Users Guide ( http://www.ti.com/lit/pdf/sprabi5 ) can be used to estimate the power consumption in your use case.  You can then make changes to estimate power reductions possible through various power savings modes.

    Tom

  • 0 in reply to Tom Johnson 16214
    TI__Prodigy 445 points
    I’m not sure Tom noticed that I did spend some time with the power estimation spreadsheet and the concomitant user guide. I believe if I pick a fixed clock frequency, Case Temp, and shutdown all the “disable-able” CorePacs and Peripherals, I should get a power number that is perhaps significantly less than when I enable everything. I’m just trying to figure out if that number is ~2.5W or 1/2W. My point on getting and estimate for example “hibernation mode 1” is that I can’t go into the spreadsheet and “enable hibernation mode 1” only. So, I was thinking, hibernation mode 1 would have to be “translated” into a list of the CorePacs and Peripherals that would be disabled in the spreadsheet to get a number in the ball park.

    I noticed that you are a CalPoly SLO Power guy. What’s the lowest number for power you can get with the estimation sheet being free to make any adjustments you want to? Is it Watts? Tenths of watts? More than ten watts? Just trying to get within an order of magnitude so I can be somewhat confident in the number I get for a “low power” mode.
  • 0 in reply to Christopher Loo
    TI__Guru* 83985 points
    Chris, Jeramei
    Is the customer still waiting for guidance on this query? There is some bench data in archives from 2012 - which was likely done with nominal samples and room temperature , that I can try to pull out, but I believe these features have no support in software and may not be a good proxy for what the customer can expect with faster process or higher temp.


    The power estimation spreadsheet may try to emulate that scenario, but the spreadsheet was not developed with hibernation mode characterization in mind.

    Does the customer have a certain power budget/goal that they are trying to meet?

    Does providing a combination of what clock and PDs will be off in hibernate mode help?

    Regards
    Mukul