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TMS320C6657: shortest method (time wise) to power down the device

Viktorija Cecil
Mastermind 18471 points
Part Number: TMS320C6657

Team,

Please help address my customer's question:

In section 6.3.2 there is a reference to a catastrophic power supply failure occurrence, and the fact that the PORn line needs to be activated if that occurs, but later in the next paragraph there is mention of a power supply monitoring solution being needed to prevent the device from being damaged long term (this seems to imply that the PORn activation will not prevent damage to the device long term).  I lack a power supply monitoring solution, but I can get at least a short warning before the power for the unit is totally lost.  This warning will be very short so the question is, what is the shortest method (time wise) to power down sequence the TMS320C6657 to prevent damage to the device long term?

Thanks

Viktorija

  • 0
    TI__Guru 54292 points

    Viktorja,

    If you don'thave a power supply monitor ... what is generating the short warning before the power to the unit is totally lost?

    Whatever the mechanism, there would need to be a way to turn off all supplies to the SoC in the event that one or more rails is damaged.

    On the other hand ... if one or more supply rails is damaged, maybe having the SoC also get damaged is not critical.  I.e., there would be no recovery from the power supply being damaged anyway.

    Regards,

    Kyle

  • 0
    Prodigy 20 points

    I will try to make a long answer as short as possible.  The only monitoring I will have of power is to look for a dip in the main rail voltage as power is being turned off, so the short duration I spoke of is between when that point is reached and the regulator goes below its minimum voltage.  I can prolong time time somewhat by adding bulk capacitance on my board with the DSP, but I do not have much space for capacitors.  

    The concern I have is more long term.  Normally I would control the power shutdown through a organized method, something like -user hits power button -system recognizes user request, system does housekeeping -and lastly,, system shuts off power.  So it that case I can gracefully turn off power, but in this case I can only do more of an 'emergency' shutdown, since I will have no warning prior to the rails beginning to dip. 

  • 0 in reply to Gale Jones
    Prodigy 20 points

    So, yes I can monitor the power supply, but it will be very primitive.

  • 0 in reply to Gale Jones
    TI__Guru 54292 points

    Gale,

    I can't guide you in detail, but it sounds like you have the right idea.  Either have the "primitive" circuit wire back to the enable input to the first and/or second stage PMIC, or have the circuit wire to a GPIO to the processor, the processor can detect the GPIO via an interrupt and react by disabling the external 1st/2nd stage PMICs either via I2C (if it exists) or via a GPIO output.

    Regards,

    Kyle