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DAC8831 grounding

kamarya
Prodigy 20 points
Other Parts Discussed in Thread: DAC8831

Hi,

I am building a board that include 8 DAC8831 and 16 ADCs interfaced to an FPGA.  I am having an issue with the DACs grounding . If i split the ground plane, i will for sure have many traces that will be crossing the separation ... did someone already use this chip ?? i am wondering if  having only one ground plane for both DGND and AGND  won't be better ?

thanks

  • 0
    TI__Mastermind 43915 points

    Hi Kamarya,

    I would recommend using one ground plane. AGND and DGND have an internal diode between the two which do not allow them to float more than +/-0.3V of one another so tying them together is recommended. You will need to be careful in your layout having all these components that the digital lines do not cross paths with analog lines especially when using one ground plane. The current return path for traces like to follow directly below the route when using a ground plane. If you are routing on multiple layers and have analog and digital lines crossing paths, running in parallel, etc. you may see some coupling effects of the digital line on the analog signal. Take a look at a few of these design notes on layout -

    http://e2e.ti.com/support/data_converters/precision_data_converters/w/design_notes/general-pcb-layout-questions.aspx

    Regards,

    Tony Calabria

  • 0 in reply to Tony Calabria
    Prodigy 20 points

    Thanks Tony for your reply, that help a lot :) !!

    regards,

    Mariam