How to use ADAU1701 as I2S Sample Rate Converter from 44.1kHz Input to 48kHz output?

Hi,

I am working on an I2S converter which needs to convert the I2S Sample rate from 44.1kHz to 48kHz as shown in the picture below.

May I know can ADAU1701 be the I2S sample rate converter? Or is there any alternative part suggested for this function?

Sincerely,

Kwan

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    •  Analog Employees 
    on Feb 20, 2019 7:47 PM

    Hello Kwan,

    The ADAU1701 does not have a sample rate converter in the part. So this part cannot be used.

    The ADAU1442, and the ADAU1452/51/50 will have sample rate converters but it is a complex part to use only as a sample rate converter. If you can use the DSP as well then it may justify the size and cost.

    There is possibly another part. Would a wafer level part be something you would consider? I would require via in pads which makes the build cost much more expensive but the part is really small. I cannot tell you more because the part is not released yet but will be soon.

    We do have an old sample rate converter, the AD1896 that is still in production but is an old part so if you need a part that has a long lifetime then this might not be the best choice.

    Another solution is to go to analog and back to digital. This is not a great solution but is possible. The ADAU1372 would be a good choice for that. You would need two of them for this solution.

    Let me know your thoughts on all this.

    Dave T

  • Hi Dave T,

    May I know when is the new part available for testing? I tested out on the ADAU1452, but it seems like the ADAU1452 is overkill in my application. And the AD1896 seems like no longer stock in most part suppliers like Digikey. We did try out using the DAC to convert it back to analog and using ADC to convert it back to our I2S format as required, but the noise is terrible. 

    Regarding the ADC, can you suggest a part for us? I see a lot of ADC from ADI is no longer in production. We are currently using the CS5343 from Cirrus Circuit, any similar part from ADI for us to refer?

    Sincerely,

    Kwan

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  • Hi Dave T,

    May I know when is the new part available for testing? I tested out on the ADAU1452, but it seems like the ADAU1452 is overkill in my application. And the AD1896 seems like no longer stock in most part suppliers like Digikey. We did try out using the DAC to convert it back to analog and using ADC to convert it back to our I2S format as required, but the noise is terrible. 

    Regarding the ADC, can you suggest a part for us? I see a lot of ADC from ADI is no longer in production. We are currently using the CS5343 from Cirrus Circuit, any similar part from ADI for us to refer?

    Sincerely,

    Kwan

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  • +1
    •  Analog Employees 
    on Feb 25, 2019 3:18 PM in reply to Kwan12

    Hello Kwan,

    If you simply connected the output of a DAC to the input of an ADC directly, then you may have had a lot of out-of-band noise that was aliasing down on the ADC. You still need to filter the output of the DAC and the input of the ADC. If you use the ADAU1372 you can operate the converters at 192kHz on both units and use the ASRCs on the serial ports to convert from 44.1kHz to 48kHZ fs without the need to brickwall filters. The filter requirements for the 192kHZ fs is very much reduced. You will not have any audio signal above 22kHz anyway so you can use a gentle filter to be at least 70 or 70dB down at 96kHz. (that is the Nyquist for a 192kHz fs sampling rate).

    Regarding the ADC. We have the older AD1974 which is still a popular part and sounds pretty good. Then there is the newer ADAU1977/78/79 which might suit your needs. You can also use the converters in the ADAU1372 but it might not be good enough for your application.

    Dave T

  • Hello Dave T,

    Thanks for your info! I try out the ADAU1977 first!

    Sincerely,

    Kwan