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Original question:

PCM5102A: Relationship between LRCK, BCK, and SCK frequencies

PCM5102A: Output level

shota nuki
Prodigy 40 points
Part Number: PCM5102A

Tool/software:

Hi team

Is there a table showing the LOUT output voltage for 24-bit audiodata?

I will be using an audio data word = 24-bit, BCK =64fS, so I will use the method where all bits after the LSB are 0.

  • 0
    TI__Mastermind 30711 points

    Hello,

    There is no table showing the LOUT voltage as you have noticed in the datasheet, and I don't recall I have seen this kind of table before. All the information regarding this IC, including any  existing applications notes , can be found in the product page. 

    Regards,

    Arash

  • 0 in reply to Arash Loloee
    Prodigy 40 points

    Sorry, but could you please provide a link to the product page?

  • 0 in reply to shota nuki
    TI__Mastermind 30711 points

    Sure, this is the first page of the IC documents in ti.com. So it is 

    https://www.ti.com/product/PCM5102A

    Sometimes you can find useful docs or application notes on similar  IC' s product page as well.

    Regards,

    Arash

  • 0 in reply to Arash Loloee
    Prodigy 40 points

    I have checked this link. Even after checking it, I could not find any information that explains the relationship between the output voltage and audio data, so I am asking. Please let me know of a document or a link that explains the relationship between the output voltage and audio data.

  • 0 in reply to shota nuki
    TI__Mastermind 30711 points

    Hello, as I mentioned above,  IF there is any additional document related to the device , it can be found on the product page.  This is true for any product. All available documents could be found in its product page. 

    I don't recall I have seen  a table for Vout vs. input data/code in any  datasheet. But you can calculate the output , for example lets say  all ONEs will give full scale of 2V at the output , and all Zeros will give 0V, similarly a mid code ( i.e,  100000....00000 ) will give the mid scale , so you can roughly calculate it based on LSB and code and reference voltage.  

    Regards,

    Arash

  • 0 in reply to Arash Loloee
    Prodigy 40 points

    This product has an output of 2.1VRMS centered around GND, so I understand it can be set from -2.9V to +2.9V.

    Is it correct that the output for "0x000000" is 0V? Is the maximum setting for positive output "0x7FFFFF"? Or is it "0xFFFFFF"?

    Also, is it correct to understand that when "0x000001" is set, the voltage is 0.35uV?

  • 0 in reply to shota nuki
    TI__Mastermind 30711 points

     Full scale of 2.1Vrms ground centers means when all zero is applied it will give the the smallest Vout which-s -2.95V and when all Ones are applied,  it will yield 2.95V. Similarly for a mid code (10000.....0000)  it should yield 0Volt.

    00000.......0001 is one LSB , so  whatever you have calculated to be your LSB then this code will be equal to that.

    you can find this equation in any EE text book: 

    LSB= Vref /  (2^n   -1)

    Regards,

    Arash

  • 0 in reply to Arash Loloee
    Prodigy 40 points

    Some devices use 2's complement, so I checked.

    Thank you for letting me know that PCM5102A is not 2's complement.

    Also, as I asked in the first question, this time we will use 24 bits, so I understand that 0.35uV per LSB is fine.

    I understand that the output voltage Vout when using PCM5102A at 24 bits can be calculated using the following formula:

    Vout＝0.35uV*(code)－2.95V

    Please let me know if I'm wrong.

  • 0 in reply to shota nuki
    TI__Mastermind 30711 points

    VP-P=5.95  ( based on FS of 2.1Vrms)  

    assuming the channel length of 24 bit, then LSB= 5.95 / (2^24  -1) =35.4uV. if you are using a 32bit channel depth,  then replace 24 with 32 and find the new LSB. If you use a 32bit channel depth but your data is 24bit, it will be padded with zeros.

    The output is code  x LSB

    Regards,

    arash

  • 0 in reply to Arash Loloee
    Prodigy 40 points

    Sorry, I made a mistake in my calculations. For 24-bit inputs, 1 LSB is 35.4uV.

    Also, the output voltage when set to 24-bit width is as follows.

    Hexadecimal notation

    code　　　　output level

    0x000000 → -2.96V

    0x800000 → 0V

    0xFFFFFF → +2.96V

    Is there a difference in understanding?

  • 0 in reply to shota nuki
    TI__Mastermind 30711 points

    Seems okay to me.

    Regards,

    Arash