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PCM5102A-Q1: Charge pump frequency and CPGND

Koyo Asaishi
Intellectual 1810 points
Part Number: PCM5102A-Q1
Other Parts Discussed in Thread: PCM5122

Hi team,

This device integrate charge pump, how much frequency for charge pump?
Customer want to avoid interference with AM/FM and LCD noise.

They have 2 sampling rate, one is fs=192kHz and sck=24.756MHz.
Another is fs=48kHz and sck=24.576MHz.

I referred https://e2e.ti.com/support/audio/f/6/t/492341 so I find charge pump frequency is related to sampling rate but clear answer is not described.

I have another question, are DGND, AGND, CPGND completely separated internally?
10.1.1 Typical Applications shows CPGND is directly connected to AGND so I don't know why AGND and CPGND have each pin.

Best regards,
Koyo

  • 0
    TI__Guru 53283 points

    Hi Koyo-san,

    The charge pump operates at around 1.5MHz. The exact frequency depends on the clock configurations, but with your two values you should see:

    fs=48kHz, CP frequency = 1.536MHz

    Fs=192kHz, CP frequency = 1.536Mhz

    You can refer to the table 131 in the PCM5122 datasheet to see the clock values.

    The ground pins are each used for a separate subsection of the device.  These are usually connected internally, but sometimes from a higher-impedance path.  Sometimes extra ground pins are used to simplify device layout, or to prevent fast transients from effecting other circuitry.  They can be directly shorted on the PCB, or isolated for noise concerns.  For the PCM510xA, the CPGND is in the analog domain, so it make sense to connect it to AGND.

    Thanks,

    Paul