Controlling SPI DAC: A Journey started.

 

2020.10.4     Get this from Paul Frost, the designer of DAC11001.   Write him a mail. 

To be clear, this device was not designed for audio but rather very high-end test and medical applications. R-2R DACs in audio is a bit of a niche application. That being said, there are some companies and hobbyists that are using R-2R DACs still (Schiit's Yggdrasil, for example). Note that the first version released is the DAC11001A, the next version will achieve tighter INL and drift specifications. The sample-and-hold circuit improves the AC performance of the R-2R by making the glitch code-independent. This removes some of the nasty harmonics that you might see in a regular R-2R design. The I2S to SPI is a bit of a problem. Fortunately, the DAC11001A features a daisy-chain mode that looks somewhat similar to I2S. I was able to create the glue logic that converts 24-bit, right-justified I2S to SPI using only 2 flip-flops, a shift register, and 7 logic gates.