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PCM5102A: Can PCM5102A be used for sampling frequencies other than common audio sampling frequencies

Sujisha v
Prodigy 40 points
Part Number: PCM5102A
Other Parts Discussed in Thread: PCM5122, PCM5102

Hi,

Can PCM5102A be used for Non-Audio application with sampling frequencies 12.8KHz, 180KHz and 256KHz? Is PCM5102A is dedicated for only common audio frequencies listed in datasheet(8 kHz, 16 kHz, (32 kHz - 44.1 kHz - 48 kHz), (88.2kHz - 96kHz), (176.4 kHz - 192 kHz), and 384KHz)?

In the datasheet, Table 10 listed only 10 common audio sampling frequencies. If I want to use PCM5102A for some other frequencies which is not mentioned in Table 10, How can I implement that?

I am interfacing  this DAC as slave and FPGA as master. So any PLL configuration can be done for Non-specified sampling frequency? 

  • 0
    TI__Mastermind 32391 points

    Hello,

    Since it is an audio DAC, I personally never used it for any  non-audio  sampling freq,  but I assume it can work but may not meet the specs of datasheet. For non audio sampling frequency, I believe you need to  the PLL.

    Please refer to datasheet as it mentions "SCK rates that are not common to standard audio clocks, between 1 MHz and 50 MHz, are only supported in software mode by configuring various PLL and clock-divider registers."

    Regards,

    Arash

  • 0 in reply to Arash Loloee
    Prodigy 40 points

    Hi,

    Thanks for your reply. But my concern is whether PCM5102A  support software mode for configuring various PLL. The DAC(PCM5102A)will support the sampling frequency of 12.8kHz, 64Khz, 128kHz, 180Khz,256kHz etc with this software mode(configuring PLL). Please confirm.

    Regards,

    Sujisha

  • 0 in reply to Sujisha v
    Prodigy 40 points

    Please find the below explanation if you are not understanding my issue,

    I am using PCM5102A in 4-wire I2S mode. Which means all the clocks - SCK,LRCK,BCK are generated from the Master FPGA and provided to PCM5102A. In this case Internal PLL will be disabled as SCK is provided externally.

    Please refer the  below table  for the sampling frequency, BCK,SCK for different systems and will be provided by the FPGA.
    Sampling Rate (ODR) (ksps) LRCK(Fs) BCK(64 Fs) SCK(128 Fs)
    12.8 12.8 819.2 1638.4
    32 32 2048 4096
    64 64 4096 8192
    180 180 11520 23040
    180 180 11520 23040
    32 32 2048 4096
    128 128 8192 16384
    180 180 11520 23040
    32 32 2048 4096
    256 256 16384 32768
    256 256 16384 32768
    Since our sampling clocks are not standard audio sampling frequency we have ensured that SCK is less than 50MHz. We would like to know the DAC performs as expected or any issues may be observed for the above configurations.
    Regards,
    Sujisha V
  • 0 in reply to Sujisha v
    TI__Mastermind 32391 points

    Hello Sujisha,

    Thanks for clarification of your question.  PCM510x family , per its users guide are hardware programmable only , so PLL can not be programmed the way you can program  PCM5122 registers. As you may  know, with PCM5122, for non audio frequencies, the PLL needs to be program, but in PCM5102A, the PLL generates SCK with reference to BCK (audio frequency) when SCK is not provided .

      I have never used PCM5102 in non-audio applications , specially when SCK is also provided like your application,  but I believe it still works -minus guaranteeing the datasheet specs. Let me see if I can find the EVM for this device and test a non-audio frequency such as fs=256k . I will have an answer by the end of next week.

    Regards,

    Arash

  • 0 in reply to Arash Loloee
    TI__Mastermind 32391 points

    Hello Sujisha,

    I found  PCM5122 EVM and I verified it in HW mode -without any need to program it , the part was able to function for various  non-audio freq that I applied through the  AP2700 series . I tried  freq up to 216K,  since  AP2700 can not go above fs of 216K. So as I said before, PCM5102 should function  with non-audio frequencies too.

    Regards,

    Arash

  • 0 in reply to Arash Loloee
    Prodigy 40 points

    Hi,

    Thanks for your effort and immediate response. Please clarify my below points,

    1.Have you checked all the frequencies that I listed in the below table? Have you observed any issues with DAC performance for any frequency?

    2. Is there any difference in 'HW mode' for PCM5102A and PCM5122? From the datasheet of PCM5122,  Asper my understanding, Connecting MODE 1 and MODE 2 pins to DGND sets the Hardware mode. Then PCM5122 will be similar as PCM5102A. Please correct me if I am wrong.

    Sampling Rate (ODR) (ksps) LRCK(Fs) BCK(64 Fs) SCK(128 Fs)
    12.8 12.8 819.2 1638.4
    32 32 2048 4096
    64 64 4096 8192
    180 180 11520 23040
    180 180 11520 23040
    32 32 2048 4096
    128 128 8192 16384
    180 180 11520 23040
    32 32 2048 4096
    256 256 16384 32768
    256 256 16384 32768
  • 0 in reply to Sujisha v
    TI__Mastermind 32391 points

    Hello Sujisha,

    Keep in mind that this is an audio DAC so performance is not guaranteed for non-audio frequencies. I tested several frequencies in the list and I did not see any issue with the device functionality.

    Today I  used the PCM5102EVM itself and here are some shots of scope with different sampling frequency ( I tried 200KHZ and 215KHz as well )

    Kind Regards,

    Arash

  • 0 in reply to Arash Loloee
    Prodigy 40 points

    Hi Arash,

    Thanks for your reply.  

    We have assembled PCM5102A on a general purpose PCB and started testing in our Lab. But we are not even getting output for 32KHz sampling frequency itself in the 4wire I2S mode. All the clocks are properly coming from FPGA and clock values are given below. But only noise is observing at the output.

    For 32KHz sampling frequency, 

    SCK=4.096MHz

    LRCK=32KHz

    BCK=2.048MHz

    and the following settings are done ,

    * XSMT pin has pulled up with a 10K res

    *DEMP,FLT &FMT has pulled down using 10k res

    Can you please review the attached schematics and let me know anything to be done apart from this. 

    AnSNS_DAC.pdf

    with regards,

    Sujisha V

  • 0 in reply to Sujisha v
    TI__Mastermind 32391 points

    Hello,

    As far as the part itself  and EVM goes, I think I have demonstrated the part works with non-audio sampling rates - even though it is an audio device. Also I don't see any issue with your schematics in general. So it seems problem might be with  the actual implementation of the schematic on your general purpose PCB or an issue with signals ( CLKs or supplies or ...)  that are getting to device- or generated internally. 

    The only thing that I can suggest to you  is to check every voltage at the pins (LDO,VNEG and ...) to make sure it is correct. Also plot I2S signals in the same window and make sure it is I2S  format as it is shown in Figure 14. I 2S Audio Data Format.

    As far as the title of the post goes, the part works fine for non audio frequencies. 

    If you have another question for this part please kindly  open a new post.

    Regards,

    Arash 

  • 0 in reply to Arash Loloee
    Prodigy 40 points

    Hi Arash,

    We have checked the voltages and I2S plots. Our observation is given below,

    1. Observing LDO voltage as 1.92V.

    2. No voltage observed on VNEG pin and across CAPP and CAPM. CPVDD is supplied with 3.3V. 

    3. I2S plots are attached. It is coming as expected in Fig14.(Yellow - LRCK, Pink- BCK, Blue - Data)

    Please let me know what will be the reason for no voltage output on VNEG pin. Will it affect DAC out?

    Please respond ASAP because we are in middle of pro building.

    With regards,

    Sujisha V

  • +1 in reply to Sujisha v
    TI__Mastermind 32391 points

    Hello Sujisha,

    In order to help users of E2E, we would like to separate the topics so E2E users can search and find their answers. As I asked you above, please start a new topic since the topic of compatibility of the non-audio sampling rate for PCM5102 was answered.

    The issue of your circuit not working with a general purpose  PCB  is a new topic  and deserves to be addressed separately. If we find it is related to the first topic, I will link it so others can benefit from it.

    Regards,

    Arash