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TMS320F28335: Microcontroller stop working at 110°C - Appears as no firmware loaded (very low current consumption) - Assumption of flash memory access issue since 2019 (datasheet rev O)

Eric Serrure
Prodigy 40 points
Part Number: TMS320F28335

Tool/software:

Hi team,

Regarding these two documents (Revision are important):

  • "TMS320F2833x, TMS320F2823x Real-Time MCUs Silicon Errata (Silicon Revisions A, 0), Rev N"
  • "TMS320F2833x, TMS320F2823x Digital Signal Controllers (DSCs), Rev O"

And our own experience of TMS320F28335:

  • The maximum flash “Program time” and “Erase time” is multiply by 8 on parts manufactured since 2020 (maybe 2019).
  • At 110°C, the consumption of some DSP (observed on around 30% of parts from 2 different batch manufactured in 2023) is the same as the one measured when there is no firmware loaded into the flash. When the temperature is decreased, the DSP come back to normal behavior (no flash erase or corruption).

We assume that something has been changed, design or manufacturing process, affecting DSP Flash memory or access to it.

Could you confirm our assumption? Have we missed a PCN?

In case of this assumption is confirmed, would you mind communicated the first batch (date code) affected by this modification?

Kind regards,

  • 0
    TI__Guru* 77410 points

    Eric,

    With regards to 

    Eric Serrure said:
    • "TMS320F2833x, TMS320F2823x Real-Time MCUs Silicon Errata (Silicon Revisions A, 0), Rev N"
    • "TMS320F2833x, TMS320F2823x Digital Signal Controllers (DSCs), Rev O"

    prior to the revO DS, we did not have a listed max for both program and erase time in the DS.  There was no change to the device at this time, adding the max was something we did to give a cap on the upper bounds, across temperature, so that the timeout of the API would not be too short across all devices.

    Eric Serrure said:

    And our own experience of TMS320F28335:

    • The maximum flash “Program time” and “Erase time” is multiply by 8 on parts manufactured since 2020 (maybe 2019).
    • At 110°C, the consumption of some DSP (observed on around 30% of parts from 2 different batch manufactured in 2023) is the same as the one measured when there is no firmware loaded into the flash. When the temperature is decreased, the DSP come back to normal behavior (no flash erase or corruption).

    For the first bullet, as long as the program or erase times are within the DS specification that is all we can guarantee on the device.  Similar to the above I am not aware of any change to the manufacturing process that took place either back in 2019 or recently.

    For the 2nd point, and the title of your post; you are seeing some percentage of devices that did work correctly at room temp(or some temp below 110), stop working once this temperature is reached.  And when this happens you observe that the current into the device is matching an unprogrammed device.  Correct?

    Are you programming/erasing at this temperature and that is not working, or based on the behavior at high temp you believe that the flash is incorrect?  Since the device works at lower temp, the flash must be intact, so whatever is happening I don't think it is related to the program/erase times. 

    When you observe this issue, does it occur if the device is power cycled or re-booted at high temp, or does it also occur if the device is already running and the temperature is increased?

    Best,
    Matthew