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DAC39J82: Multiple DAC39J82 sharing the power rails

Arunkumar Palanisamy
Prodigy 160 points
Part Number: DAC39J82
Other Parts Discussed in Thread: AFE7444

Hi,

There are three DACs used in our design. All three operate at different sampling and update rate.

Will there be any impact on performance if the power rails are shared? Example: Powering all the DAC's analog supply from single source after passing through ferrite bead.

Thank You.

  • 0
    TI__Guru* 91947 points

    Arunkumar,

    If you plan on using the DAC PLL's, it is highly recommended to isolate the VDDAPLL18 power supplies which would include ferrite beads. Isolate the other critical supplies per the data sheet (VDDCLK09, VDDDAC09, and VDDDIG09) using filtering with ferrite beads. I good example for a power scheme is attached. This is a board that used two AFE7444 parts which have both ADC's and DAC's inside of them.

    Regards,

    Jim 

    Multiple AFE7444.pdf 

  • 0 in reply to jim s
    Prodigy 160 points

    Hi Jim,

    Thanks for the response. 

    I tried to access the AFE7444 data sheet for checking the power pin details to understand the separation, It requires permission and it have requested for access.

    Mean while, could you check the attached power tree that is planned. If comments are provided with reference to that, it would be easier for us grasp the reply.

    TI_DAC_Power_Tree.vsd

  • +1 in reply to Arunkumar Palanisamy
    TI__Guru* 91947 points

    Arunkumar,

    The power tree looks good. Just make sure the LDO's are rated high enough to be able to supply the required current. I would also recommend using suppression filters, like the Murata NFM31PC276B0J3, on the switcher supply used by VDDDIG09. 

    Regards,

    Jim