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PCM5122: Left-Justified Data & No Audio Output

Gokhan Ozcetin
Prodigy 20 points
Part Number: PCM5122


Tool/software:

I have created a PCB where PCM5122 is used as follows;

- ATT2, ATT1, ATT0, MAST, AGNS, MODE1, MODE2, FLT, SCK pins are grounded.

- FMT and XSMT are high

- I have perfect 3.3V on analog & digital supply, 1.8 volts on LDOO (self regulated), -3.3V on charge pump output

- I am supplying a 24 bit 96 khz audio data with 6.144Mhz BCK. On the PCM input pins I can observe BCK, WS and Left Aligned Data (LSB aligned to the 1st clock).

However I am getting no output. Changed DAC several times. There seems no HW fault.

What am I missing?

  • 0
    TI__Mastermind 31701 points

    Hello Gokhan,

    The relationship b/w Fs (LRCLK) and BCK is given by the following equation:

    BCK =  # of Ch  x  Bit Depth  x  Fs

    for the values you mentioned above, I get 4.608MHz for BCK but you are using 6.144MHz. Probably you are using a 32 bit in your calculation. 

    BCK= 2 * 24 * 96KHz =4.6080MHz

    BCK= 2 * 32 * 96KHz = 6.144MHz

    I think BCK correction should fix the problem.

    Regards,

    Arash

  • 0 in reply to Arash Loloee
    Prodigy 20 points

    Well, this does not comply with the explanation given in the datasheet below

    Although the actual data is 24 bits, the WS and BCK encapsulates it as 32 bit data and I see no explanation to get no output. It should in anycase output something even if the data is not fully 32 bits. Isn't that correct? It should not be a full zero output on the scope

  • 0 in reply to Gokhan Ozcetin
    TI__Mastermind 31701 points

    I can see how datasheet may  not be very clear here , but  the above equation  governs the relationship b/w fs and BCK and it fits the table in datasheet.

    From my experience,  once the correction is made  the output will appear.

    Arash