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TMS320F28069M-Q1: Piccolo Power Pad Question

ROBERT SHAFFER
Prodigy 145 points
Part Number: TMS320F28069M-Q1

Due to the limited supply of the TMS320F28069MPZT, is it OK to use the Power Pad version (TMS320F28069MPZPQ) in its place as an alternate if it is not soldered to the board? My layout does not have the power pad underneath and would require a new layout if need be. slma002h states it must be soldered to the board but my application works fine (temperature within spec) with the non Power Pad version.

  • 0
    TI__Mastermind 41385 points

    Robert, 

    The device has not been qualified in this manner. It is a requirement that this power pad is soldered to ground for the sake of thermal dissipation, although this pad is not actually connected to the device's VSS.

    I will not recommend this practice. It is unclear how the thermal dissipation will be affected, particularly for an automotive application where the die is more thermally stressed. 

    Regards,
    Cody

  • 0 in reply to Cody Watkins
    TI__Guru 71785 points

    Robert,

    I spoke with Cody, and need to offer a clarification/correction to the response above. 

    The Power Pad is needed on the Q/S grade devices as those are designed to support 125C operation, and in the temp range 106C-125C, the power pad itself is needed to remove heat from the package to maintain stability/die temperatures.  For those applications that require that extended temp range, soldiering the power pad is required.

    The non-power pad device is sufficient to handle the "T" grade of temperatures up to 105C max, which is your application today.

    In your scenario, replacing a "T" device with a "Q" device and not soldiering the power pad is OK.  This is because you are still using the device as a "T" temp range device so the extra conductivity of the power-pad is not needed in that temperature range. 

    Or to put it another way the power pad package w/o soldiering the power pad to the ground plane of the PCB will have the same performance as the non-power pad package for a "T" grade application.

    Let me know if you have any additional questions.

    Best,

    Matthew

  • 0 in reply to MatthewPate
    Prodigy 145 points

    Hi Mathew,

    Thanh you for your help!

    Rob

  • 0 in reply to ROBERT SHAFFER
    Prodigy 145 points

    Hi Mathew,

    One final question, is the silicon the same between the two parts?

    Rob

  • 0 in reply to ROBERT SHAFFER
    TI__Guru 71785 points

    Rob,

    Yes, the silicon is the same.  Q material has more testing and qualification than non-Q, but no difference in the silicon.

    Best,

    Matthew

  • 0 in reply to MatthewPate
    Prodigy 145 points

    Thanks again Mathew.