I'm going to use this ADAU1966A in my upcoming project for an audio application. We're having 3 different audio bandwidth in our application.
(a) The first type will have 10KHz audio bandwidth with 31.25KHz sampling rate.
(b) The second type will have 2.4KHz audio bandwidth with 7.81KHz sampling rate.
(c) The third type will have 150Hz audio bandwidth with 976Hz sampling rate.
Each type will have 8 Audio output channel. So totally 24 audio output is required for us. Hence we've preferred to use two ADAU1966A for this 24 audio output requirement. The first ADAU1966A will be for audio type (a) & (b) by making the (b) type also with 31.25KHz sampling rate. The second ADAU1966A will be for audio type (c) with 976HZ sampling rate. We're preferred to operate this ADAU1966A in slave, stereo left justified mode with direct MCLK input to the DAC by bypassing the PLL section. We're having a following query to proceed further with the implementation.
1. The sample Rate Select (b00) in DAC Control 0 Register is stating 32/44.1/48KHz. Is it recommended to use any of these three sampling rate values or anything within this range we can use?
2. Can we use below 32KHz sampling rate with this ADAU1966A? Because for audio type (c), the bandwidth itself 150Hz. Hence there is no use of going more than 32KHz sampling rate?
Hello Loganathan N,
Yes, you can operate at any rate below 32kHz. I cannot say that I have ever tested it as low as 1kHz but it should be possible. When you are direct clocking you are in control of the clock rates inside the part. The digital filters need the master clock to be 512 x fs to give it enough cycles to complete so as long as that is met then it should work down to really low frequencies. On the upper end you will run into the maximum speed of the clock pins and internal circuits so there is an upper limit.
Let us know if it work for you. Like I said, I have not tried it. I don't think the Audio Precision will go that low.