Electronic – Using a “non-audio” oriented DAC IC as an audio DAC

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I'm starting a project that consists of a simple embedded 16-bit PCM audio player, where no actual DSP takes place, only plays PCM and outputs something you can then amplify.
I am currently searching for my DAC IC, and I'm hesitating between these two references from Texas Instruments :

  • The DAC7642, a "non-audio" applications-oriented R-2R DAC, parallel data input.
  • The PCM1773, an audio-applications-oriented sigma-delta DAC, serial data input

The thing is, even though the DAC7642 isn't meant for actual audio applications but rather for industrial/motor control applications, it uses the R-2R architecture which I highly prefer over the Sigma-Delta one, and it has parallel data input which I find way more convenient than the PCM1773's serial data input.

My question is: Are there any big drawbacks that should prevent me from using the DAC7642 as an audio DAC (Increased noise in audio output? Mediocre performance at clock rates needed by audio to output analog voltages at rates like 44.1 kHz?) Or can I just go with it and forget about the PCM1773?

Best Answer

Are there any big drawbacks

  1. Price. It looks like DAC7642 is 8-10 times more expensive
  2. Nosie performance. The DAC7642 is weirdly specified but it looks like maybe 14-bit are actually usable for audio and the linearity and monocity errors eat up the rest.
  3. Clocking: You need to clock out samples are regular rate and audio is quite sensitivity to clock jitter. I'm not sure that the DAC7642 has a settling time that's independent from the data.
  4. System integration. For the audio DAC you just pop down a clock chip, hook up a few I2S lines are you are done. For the DAC7642 you need to build a large parallel bus and make sure all your timings are correct.
  5. You may need extra anti aliasing filtering.

The PCM1773 is optimized for audio in terms of interface, ease of use, configuration and performance (especially bang for the buck). The DAC7642 is designed as an asynchronous control DAC for a completely different application. It's going to be a lot of work to make it work. Even if you get it running it still won't perform as well as the PCM1773 .

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