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REGARDING CURRENT REQUIREMENT FOR TMS320C6678ACYPA25

Sakthi Annamalai
Intellectual 610 points


Hi,

       We are using 1.25GHz IND Version 6678 for Prototyping.  I have used the Power Spreadsheet  to calculate the Current requirement .  I have attached the same.  In spreadsheet ,the CVDD voltage is fixed at 0.85V.  But it is a variable voltage from 0.7 to 1.1V through VID interface. How to set the CVDD at 1.1V in spreasheet

   Also,I found the difference in the current specification  for 1.25GHZ processor between the attached spreadsheet and following  TI Link :http://www.ti.com/analog/docs/refdesignovw.tsp?familyId=64&contentType=2&genContentId=149652#sysmonsup.

  The TI link says CVDD requirement is 12.9A for 1.25GHz@85'C.

Please confirm which one i should consider for selecting Power driver.

Regards,

Sakthi.A

4643.5468.C6678_Power_Consumption_Summary_Rev3_4.pdf

     

  • 0
    TI__Guru* 81335 points

    Hi,

    Moved this thread to correct forum for faster response.

    Thank you.

  • 0
    TI__Mastermind 30825 points

    Sakthi,

    The Current provided in the Power Spreadsheet is the worst case current, no matter which voltage level the SR was programmed into the device.  The SR CVdd value is taken into consideration when power screening the devices.

    The reference you pointed to with the 12.9A has an associated note stating ->

    • Consult the C667x power spreadsheet for your exact power requirements.

    I looked at your power spreadsheet, and you're SP & CC utilization numbers are extremely high.  Actually high enough that it's not realistically achievable. 

    I'd recommend reading the pop up when clicking in the box to set the %SP Utilization in particular.  A typical high performance application is going to have this box at about 27-30%, you have it at 60% and CC at 20%.  This simply isn't realistic in real world applications based on experience.

    I'd suspect the same is true for your IO, which most everything is set to 80%.

    Pulling these numbers back to more realistic implementation and you'll be much closer to the 12.9A  initial estimate provided by the power solution page.

    Best Regards,

    Chad