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DS90UB949-Q1: Interfacing to a PCM1753DBQ I2C DAC for HDMI Audio Output

David Canestrari
Prodigy 40 points
Part Number: DS90UB949-Q1

 Hi, we are wanting to interface a PCM1753DBQ I2S DAC to a DS90UB949-Q1 to strip out stereo (L/R) audio from an Input HDMI feed.

On the DS90UB949, there are 3 I2S pins:

  1. I2S Data output: pin 32 of 949
  2. I2S LRCK(channel sel) : pin 33 of 949
  3. I2S_bck ( audio bit clock ): pin 34 of 949

 

Now the question is,  PCM1753DBQ requires 4 pins. In addition of 3 above , it requires system clock to function. Which section will generate system clock? We found SCLK ( pin 6 of 949) but this is in auxiliary I2S. Will this works since the other pins are of slave i2s section? Also can we somehow interface the remaining pinouts of DAC (FMT / Mute / Demp) with 949?. L det and R det are interfaced with controller already.

Snippets of circuits:

 

Can you recommend the proper way to interface this DAC to the DS90UB949 Deserialzer?

Thanks!

  • 0
    TI__Expert 6715 points

    Hi David,

     

    The system clock input for the PCM1753DBQ is not something the DS90UB949 serializer can provide when extracting I2C from HDMI. As shown in the table below from the PCM1753DBQ datasheet, the system clock needs to be a certain multiple of the sampling frequency (fs). Some devices like our DS90UB940 deserializer have an additional MCLK output for I2S that can be set to a multiple of the I2S clock to serve as the DAC's system clock. However, this is not a feature of the I2S interface of DS90UB949 used to strip HDMI audio as the aux audio interface you pointed out is not able to output the stripped HDMI audio. The PLL170x family of multiclock generators is mentioned in the datasheet as an option to generate the system clock for the PCM1753DBQ.

     

     

    As for connecting the remaining pinouts of the DAC with the DS90UB949, they can be connected to the remaining GPIO of the DS90UB949 and configured to output a 0 or 1 locally.

     

    Please let me know if you have any additional questions.

    Sincerely,

    Ryan