ADAU1777(1772) stand alone codec.

traxman Question

Mar 12, 2018 00:00

Hello

Can I use Adau1777(2) as a smart stand alone (mic preamp, a few filters+limiter) codec with I2S -4Wire interface (common clock LRCK, BCLK, separate data SDI, SDO) as in the picture?

Is it possible to work ADAU177(2) with low sampling rate 11-32kHz?

J2 is master I2C output port from host processor to ADAU DAC, J1 is slave port to get data from ADAU ADC.

Host processor can be configured as Master or Slave.

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DaveThib Reply

Mar 12, 2018 00:00

Hello traxman,

Yes, this is a good use for the part. What is really useful is the ASRCs that are part of the serial ports. This allows you to have the 1772/1777 run on its own master clock on its own crystal and then operate the serial port as a slave. So the host processor will be the master for the serial ports. Then you can send it any sample rate from 8kHz fs up to 192kHz fs and it will simply follow the sampling rate and do all the conversions with no interaction by the host. This is very handy for applications where you will be changing sources like SPDIF, Bluetooth or from an Ethernet source of audio. You do not have to worry about locking a PLL to the incoming clock and generating a master clock. It is not needed.

If you need the small size then the 1777 is a good choice. If latency is the issue there still is not a good reason to use the 1777 because when running the audio out of the serial port at low sample rates, the difference in latency will be swamped by the time it takes to shift out data at a low sample rate. This is not a problem with the parts, just a fact of life.

So the 1772 would probably be the best choice. There is also a differences in the packages of the two parts. Internally, they are very similar.

For others that might read this, if no pre-processing is needed, only ADC and DACs, then using the ADAU1372 will give you the same clocking flexibility.