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PCM5310 problem: clipped output

toshi-e2e
Genius 4790 points
Other Parts Discussed in Thread: PCM5310

Our customer has been evaluating PCM5310 on their own designed H/W, and reported that the line output signal was clipped at 3.3Vpp under below conditions.

1. Signal pass:
    AIN2L → PCM5310（ADC）→（I2S）→ DSP →  （I2S）→ PCM5310(DAC) →　LO1L
2. ADC input level: 2V_rms　Sine wave
3. Analog input gain = 0dB,  ADC attenuation = 0dB, DAC attenuation=0dB
4. In case of Analog input = 2V_rms (5.6 Vpp), LO1L output of both  upper side and bottom side is clipped at 3.3Vpp.
5. Output signal is not clipped when decreasing analog input signal level to 3.3Vpp.
6. Confirmed the power supplies.
    VREFAD1 (62pin) = VCOMAD(64pin) = VCOMDA(25pin) =1.64V
7.The register setting is the same as  [Table 8. Recommended Register Settings When Powered On (continued)] of datasheet.

Does anyone have any suggestion or advice  for solving this problem?

Thanks in advance.

Regards,
Toshi

 

 

  • 0
    TI__Guru**** 189399 points

    Hi, Toshi,

    Sorry for the delay. Since the PCM5310 is an audio converter, I am going to move your post to the audio converter forum.

    -d2

  • 0 in reply to Don Dapkus
    TI__Guru 56086 points

    What's your VCCH voltage level?

  • 0 in reply to Dominik Hartl11
    Genius 4790 points

    Hi, Hartl-san,

    Thanks for your responce.

    VCCH is 9V.

    Also, I would like to get the analog input equivalent circuit for understanding input structure.
    Because I think the circuit in the data sheet is strange.

     

  • 0 in reply to toshi-e2e
    TI__Guru 56086 points

    Are you able to get 2Vrms using the DAC alone (without the ADC)?

    What do you think is strange with the published input circuit?

    Please attach an excerpt of your schematics showing how you connect the PCM5310

  • 0 in reply to Dominik Hartl11
    Genius 4790 points

    I'll try to ask  to customer whether output of 2Vrms can do by only DAC or not.

    Anyway, my question of analog input is about the internal circuit of IC.

    As my understanding,  VCCH is for the driver supply voltage. isn't it? And the operating voltage of Op amps of analog input is Vccad = 3.3V.

    If my understanding is correct, the gain of op amps of analog inputs are  equal or less than 1/2 for supporting 2Vrms signal level, and also it requires common bias (maybe equal to VCOMAD).

    But an analog input circuit of the datasheet shows x1 op amps without bias.

    So that, I would like to know  the  internal analog input equivalent circuit.

     

     

      

     

  • 0 in reply to toshi-e2e
    TI__Guru 56086 points

    VCCH = 9V is required for the driver to achieve 2Vrms.

    The input to the ADC is compatible with 2Vrms signals. Please make sure that the analog input gain is confirmed to be 0dB. I'll check with the systems engineer for further advice.

  • 0 in reply to Dominik Hartl11
    Genius 4790 points

    I confirmed the analog gain was 0dB.

    Also, custmer reported that when an analog signal level is 4.8Vpp, the ADC results does not have any clamped condition.

    So, that, I asked customer to check the I2S  data for DAC output.

    Anyway, I am looking forward to receiving the analog input equivalent circuit.
    Customer is wanting to get to know it.

     

  • 0 in reply to toshi-e2e
    Genius 4790 points

    Customer checked the output level and the results are as follows;

    Max: 0x7fffff 　　->　5.61[V]

    Min: 0x800000  ->　2.14[V]

    Max - Min:  ->  5.61 - 2.14 = 3.47[V] 

    OFFSET: 0x000000  ->　3.81[V]

    Could you please give me your comment and advice  for this results?