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What are the DDR2 Power groups?

Traian Mitrache
Prodigy 180 points
Other Parts Discussed in Thread: TMS320C6748

What is the purpose of the DDR Power Groups, and how are they to be used/connected?

  • 0
    TI__Guru* 84175 points

    Traian

    I am not sure I understand your query, can you please clarify/elaborate? Can you also clarify if you are asking this in context of c6748? If yes, the DDR2/mDDR power pins for listed as DDR_DVDD18 in the C6748 datasheet.

    Regards

    Mukul

  • 0
    TI__Guru*** 125430 points
    1. What device are you using?
    2. What do you mean by "power groups"?  If you see this term in the documentation somewhere please cite the literature number and page number so that we can understand what you're asking.

    Thanks.

  • 0 in reply to Brad Griffis
    Prodigy 180 points

    1. Using TMS320C6748

    2. In the TMS320C6748 data sheet (SPRS590A) page 65: DVDD3318_A,B and C are refered to as "POWER GROUP A, B and C"

    I did a search for "power group" in the pdf and couldn't find any info on them.

  • 0 in reply to Traian Mitrache
    TI__Guru*** 125430 points

    Those rails are not related to DDR.  Those are for the I/O rails.  This device gives you the ability to choose whether you want GPIO to be 3.3V or 1.8V.  The granularity of this decision is by "power group".  For example, if you look at the definition of the /RESET pin in section 3.8.1 you'll notice that under the "power group" column it is listed as "B".  That means that when you take the device out of reset you should pull the signal to the DVDD3318_B rail.  Similarly the SPI pins are shown in Section 3.8.7 as being part of power group A.  So if you want 3.3V SPI connectivity you should connect DVDD3318_A to 3.3V, otherwise you can connect it to 1.8V for 1.8V SPI.