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DM368 EVM - 1.2V VDD12_PRTCSS verses 1.35V VDD12_PRTCSS

Nate Wennyk
Prodigy 40 points

Hi;

In the datasheet for the DM368, it lists the voltage range of the PRTCSS core voltage to be between 1.28V to 1.42V with nominal being 1.35V. The evaluation board for this processor is only supplying 1.2V to the PRTCSS core and I am wondering if this is a supported mode of operation for this device. If so, what effects will this have on the device's operation?

Thanks;
Nate

Links:
http://www.ti.com/lit/ds/symlink/tms320dm368.pdf
http://support.spectrumdigital.com/boards/evmdm368/revg/files/EVMDM368_revg_Schematics.pdf 

  • 0
    Guru 31670 points

    Nate,

    Check the document SPRUFJ0A.pdf. According to this 1.2v should be sufficient for line. Also it is just to keep the RTC alive, so I think it may not affect the operation of the chip other than loosing the RTC time value, if at all any issue occurs.

  • 0 in reply to Renjith Thomas
    Prodigy 40 points

    Hi Renjith;

    I have checked the document and it references the DM365 PRTCSS which has been specified to run at 1.2V PRTCSS core voltage. The new chip, DM368, has a slightly higher PRTCSS core voltage of 1.35V, and I just want to make sure I'm not going to decrease the reliability of the RTC by implementing it as TI has done on their evaluation board. Losing track of time would be bad and TI has a policy of not supporting use-cases that operate their device outside of the specified typical operating conditions. With their evaluation board designed to operated outside of the typical operating conditions and the lack of DM368 PRTCSS specific documentation, I'm starting to wonder if TI also applies their policy to themselves.

    It seems like TI has not updated the supporting documentation on this matter for DM368.

    Cheers;
    Nate

  • 0 in reply to Nate Wennyk
    Guru 31670 points

    Nate,

    I understood your problem. But since there is no harm in trying 1.35v you can go ahead with 1.35 v in your design and try. Anyways a little higher voltage for RTC will be better than 1.2v. I'm not a hardware expert, I may be wrong in my assumption.

  • 0 in reply to Renjith Thomas
    Prodigy 40 points

    I agree that 1.35V is fine for the actual design. However, for evaluating the DM368 PRTCSS on TI's evaluation board, I want to make sure that my tests will be valid and that I will have TI support even though technically the PRTCSS core voltage is outside of the typical operating conditions for the device. It strikes me as odd that they would build an evaluation board that has this issue and provide no documentation stating they support this specific use-case.

    Cheers;
    Nate