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PCM1807: Oscillator for various chips or SCKI and BCK shared line

ManuelGómezGalánOpt
Prodigy 60 points

Part Number: PCM1807

Hello,

I am modifying an old design where a DSP generated a MCLK for the slave devices from an oscillator (12.288MHz). I have changed the DSP and the new one cannot output a MCLK, so I am stuck at this point. I am working at 48kHz of f_s and a relationship of 256 between BCLK and LRCLK.

I have 2 questions here:

  • Can I use the same oscillator (ABRACON ASFL1-12.288MHz-LR) for various components? In my case I do need it for the DSP and this chip, at least, and then I am using a second ADC (PCM1895) where it can work with an internal PLL with the BCLK. So at least it would need to drive the DSP and this PCM1807, and the best case would be for the three chips. If this option is possible, what would I need? Just split the clock line near the oscillator output and add terminating resistors?
  • If this option is not possible, I would like if the SCLK and the BCLK can be driven by the same signal, as they share the same frequency (48000 * 256 = 12.288MHz)

Thanks in advance!

Best regards,

Manuel

  • +1
    TI__Mastermind 49730 points

    Hi Manuel,

    Knowing that you want to send data from the PCM1807 to the PCM1895, I recommend driving all 3 with the Oscillator. In order for the PCM1895 to receive and transmit the digital data correctly, the two devices must be synchronous. Splitting the clock with terminating resistors should work.

    If it doesn't work, you can tie the SCLK and BCLK together. Again terminating resistors will help eliminate reflections, but ideally it will work.

    Best regards,

    Jeff