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Ask for some general guide-lines to use DAC5687

Huy Nguyen76540
Intellectual 445 points
Other Parts Discussed in Thread: DAC5687, DAC8814

Hi all,

Currently, I need a DAC chip for my design and I try to evaluate DAC5687 chip.

However, from its datasheet, I got many registers to set up for it to work and there are many items that I do not understand how to set up.

For example: how to set hpla or hplb bit in the VERSION register, how to determine FIR filters are needed or not, or whether to use NCO or QMC block and how to set their frequencies and phases

Sorry, I do not have much knowledge about signal processing.

I just understand clock mode, interleaved input and FIFO features of the chip.

Previously, to use DAC, I just need to know the Fsig, and Fdac only, but now, it is more complicated with FIR, NCO or QMC block, etc,

If I have some input requirements like below:

    - The designed output frequecy = Fo

    - The input data rate = Fsig

    - The sample rate of DAC = Fdac

Could you give me some general guide-lines about how to set up programming registers of DAC5687 in order to use it correctly?

 

Thank you,

HuyNguyen

  • 0
    TI__Guru* 78874 points

    Huy,

    You can refer to the attached document for more information of the DAC features. These features are meant to provide more flexibility to your system design. For instance, interpolation filters allow you to use a slower data rate interface while using the DAC analog core at its maximum speed. This may possibly reduce the cost of your FPGA/ASIC since a slower speed grade may be designed in. At the same time the DAC images are pushed out farther.

    The NCO allows flexible output frequency placement, and the QMC allows the designer to tune out I/Q modulation artifacts such as sideband and feedthrough.

    Your setting really depends on your system requirement. If you have a particular system requirement, please let me know and I can help you set it up. 

    -KH

    HighSpeed_DAC.pdf
  • 0 in reply to Kang Hsia
    Intellectual 445 points

    Hi Kang,

     

    Thank you for your reply.

    However, I think it is more complex for my application of a MP3 player.

    I have found another DAC chip from TI that can satisfy my requirement. That is DAC8814.

    Using DAC8814 is simple while it still provides fast settle time.

     

    Best regards,

    Huy