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PCM1798: PCM1798 No analog signal output

Ning Li
Intellectual 760 points
Part Number: PCM1798
Other Parts Discussed in Thread: TAD5242

Tool/software:

Dears,

The signal goes through KT56(RF SOC) to output I2S and then to PCM1798, but PCM1798 does not output the analog model,and I test all the audio data format.
I2S: LRCK 48KHZ BCK 3.072MHZ MCLK 12.288MHZ , SDOUT with data output
PCM1798 MUTE pin 0 RST 1 DEM 0

Pls kindly help to check it.

Shcematic and pcb layout pls find attachfile.

Thanks

  • 0
    TI__Mastermind 47845 points

    Hi,

    Our expert on this device is out of office today and will return Monday to follow up with you.

    Thanks for your patience,
    Jeff McPherson

  • 0 in reply to Jeff McPherson
    TI__Mastermind 31521 points

    Hi,

    This is a 24bit part and Looking at your clk values, there is a mismatch.

    BCK= # of Ch x Ch depth x  fs =2x24x48K=2.304MHz

    Instead of 2.304MHz, you are using a wrong value for BCK. Please change it  and retry again . It should work.

    side note: I would use a higher value pull up resistor for reset pin. Also the output is  current,  so you need to convert it to Voltage and filter it as well.

    Regards,

    Arash

  • 0 in reply to Arash Loloee
    Intellectual 760 points

    Dears,

    KT56 can only output 3.072MHz as the master, but cannot output 2.304MHz,Could you please help me check if there are any better solutions.

    Thanks

  • 0 in reply to Ning Li
    TI__Mastermind 31521 points

    Hi Ning,

    you have 2 options which might not fit your situation:

    1-Use the correct BCK for your 48k sampling rate , which means find a way to send the correct clk of 2.304MHz

    2-Change the part with a 32bit part such as TAD5242 and use your 3.072MHz

    What you have right now,  needs a different bit clk and I have no other suggestions but option 1 as you don't want to change the part  at this point.

    I am not a fan of clk divider for I2S but you can explore that option too. 

    Regards,

    Arash