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Analog or Digital Audio Interface

Question asked by MarcvE on Nov 16, 2017
Latest reply on Nov 29, 2017 by DaveThib

For an audio application we have already identified some boundary conditions to which we now want to find the best suitable soluton.


Boundary conditions:

1. The clock from the real-time system is expected to be 8 kHz. The sample rate should be supported by all components, so no anti-alias filters need to be implemented.

2. The latency from the analog input to the analog output should be minimal.

3. The microphone should have linear transmission behavior in the relevant frequency range up to 8 kHz and have the lowest possible phase rotation.

4. Up to 4 microphones must be read synchronously.

5. The amplifier should have a power of at least 2 x 25 W at 8 ohms.

6. The cost of the components should be as low as possible.

7. The distance between the microphones and the board is up to 1 m.


Now there are different options. So far, we've been relying on the ADAU1372 codec because it has a low latency and provides the appropriate number of IOs. Now, however, we have seen that new MEMS microphones have already integrated an I2S interface. In addition, there are amplifiers which also have an integrated I2S interface. In this case, the audio codec wouldn't be necessary. Certainly one must consider that I2S lines are likely to be susceptible to EMC interference for the planned distance to the board. For the amplifier, it would be no problem because it is placed on the board. Do you have any recommendation out of the analog devices portfolio?