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DSD1791A: Dynamically varying the sampling freq to change the freq of the output...

Matt Hosler
Prodigy 245 points
Other Parts Discussed in Thread: DSD1792A, PCM1792A, PCM1794A

I am interested in using the DSD1792A DAC for an unconventional application. We need to produce a 20-40 kHz sine wave with 120 dB of dynamic range as a feedback signal to a sensor. We want to output the same values of a sine wave (min,max,and zero), but dynamically vary the sampling frequency to change the frequency of the DAC output. Looking at the DSD1792A datasheet, it seems this part will work for us by interpolating the data we send it and producing the sine wave with our required dynamic range. I do not have any experience with audio electronics, however, and do not fully understand how this part works. Are we able to change the input sampling rate to anything we want, or are we stuck with the default 44.1 kHz, 96 kHz, etc data rates? How does the upsampling for interpolation and sigma-delta conversion take place? Does the part use the clock from the SPI interface or does it generate its own clocks at specific frequencies?

  • 0
    TI__Guru**** 189399 points

    Hi, Matt,

     

    DSD17xx has DSD(64fs 1bit data stream) input capability, but in this application, PCM1792A(SW control) or PCM1794A(HW control) will be good fit for I2S data input application.

    PCM1792A/1794A is 127dB DAC, it is required I/V converter. PCM1791 is 113dB DAC but I/V is integrated, it has voltage output.

     

    Whichever our PCM179x DAC has synchronization circuit for SCK/BCK/LRCK, even if sampling rate is changing continuously it should work.

    But basically our DAC was well characterized at popular audio fs such as 32/44.1/48KHz,96KHz and 192KHz, we need to ask customer to evaluate carefully at 20KHz-40KHz fs.

    And SPI input is not audio data input, it is used for register control purpose. 

     

    -d2