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PCM5101A: PCM5101 FFT Plot using a 1-kHz tone (–60dBFS) from DC to 300 kHz

Part Number: PCM5101A
Other Parts Discussed in Thread: PCM5102A

Dear Support team,

My customer will use PCM5101A in their AVR application.

They are in trouble with the peak noise appearing at 48 kHz and 96 kHz.

 AVDD = CPVDD = DVDD = 3.3 V, fs = 48 kHz, no audio data input
* RED Line : PCM5101A No SCK input (PLL operation)
* BLUE Line : PCM5101A With SCK input (PLL stop)

In Figure 11 on the PCM5101A data sheet, PLL is stopped by inputting SCK = 512 fs.
We do not have PCM5101A Evaluation Module. (PCM5101EVM-U)
In normal operation I think that there is no peak noise at 48 kHz and 96 kHz by 8 times oversampling.

Is there an "FFT plot using a 1-kHz tone (–60dBFS) from DC to 300 kHz" measured under the condition without SCK input (SCK = GND), fs = 48 kHz, BCK = 64 fs?
If measurement data of this condition does not exist, can you measure it?

Best Regards,
Hiroaki Masumoto

  • Masumoto-san,

    I apologize for this post going without a reply for the last couple of days. This thread has been assigned and you should see a response soon.
  • Hi Masumoto-san,

    Unfortunately I do not have the capability to measure out to 300kHz in my lab, but I have collected 0-131kHz FFT with PCM5102A on the EVM.  This is with PLL being used and -60dbFS input signal at 1kHz. 

    I suspect that you have some digital crosstalk from your board layout if the digital signals are so prevalent on the output. Do you have a low pass filter on the DAC output as well?

    Thanks!

    Paul

  • Paul-san,

    Thank you for your kindly reply.
    This measurement result is my inquiry.

    I will explain it to my customer.
    The low-pass filter of the customer's circuit diagram has the same circuit configuration as the recommended circuit of the data sheet.
    I ask the customer to check the digital audio input circuit and power supply line.

    Best Regards,
    Hiroaki Masumoto