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PCM1681: Output of clipped SINE waveforms

shuji kiyama
Prodigy 60 points
Part Number: PCM1681

Tool/software:

Hello, experts.

Please tell me about the output of the clipped SINE waveform of the PCM1681 as soon as possible.

The figure below shows the circuit configuration and the observation waveform when the clipped SINE waveform is output from the FPGA.

At 1 kHz and 2 kHz, the waveform is output normally, but at 3 kHz, the waveform is not output properly.(Red arrows)

The output data from the FPGA to the DAC is shown in the figure below.

The PCM1681 is the H/W control, LRCK = 16kHz, MCLK = BICK = 4.096MHz (=256fs).

The LPF circuit is shown in the figure below.

Please tell me how to output the clipped 3kHz (the same as the output of the FPGA) from the PCM1681.

Best regards.

Kiyama

  • 0
    TI__Mastermind 28471 points

    Hello Kiyama,

    Please disconnect the load and have a simple LPF first and verify the problem is still there and it is not coming from the loading of your active filter.

    Another test that I need you to do next,  is  to directly send a -1dBFS sinewave to the DAC and monitor the outcome( with your filter still removed and simple LPF in place)

    Would you please confirm the channel depth and number of channels you are using. 

    If using HW or SW control what is FMT0/1 values?

    Regards,

    Arash