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Original question:

PCM4104: No Output

PCM4104: PCM4104 channel test unusual

Crystal Li
Prodigy 100 points
Part Number: PCM4104


hello all,

there have a problem that PCM4104 set fs=96kHz,TDM4, noise is normal, THD+N is unusual:

1. when use CH1 and CH2 data, the THD+N of CH1 is -95dB,and CH2 is only -80dB;

2.when use 4 Chanel data, the total THD+N is about -78dB;

3.try to adjust the capavitance value of Vref+ and Vref-  is not useful;

4. try to separate the power supply of Vref、VCC1、VCC2;

5.when Vdd=+5V, Icc should be 32mA,but customer test is Icc=67mA;

Many thanks, this could help me to find more opportunities from customers, thanks for your supply.

  • 0
    TI__Mastermind 31741 points

    Hello Crystal,

    I want to make sure i understand you correctly: In the first case they are using only 2 channels and channel 1 has better THD by 15dB.Then when they use all 4 channels , all 4 channels have  the same THD of -78dB?

    1-Can they monitor the Vout of each channel and see if it is what they expect for all channels together?

    2-Please  monitor VREFM and VREFP at the pin for each channel to make sure it is reading correctly

    3-  please check the data format and make sure input data bits is not shifted.

    4-Please  use one channel at a time and see if they would get the THD that we expect. If all channels are ok individually but not okay all together then I would still doubt the input data is getting to channels correctly or not.

    5- Try at 48K and see if Supply current is within 32 to 40mA, if you are getting twice the value, then  I think you are using 2 DACs, not one! Again I would check my input data.

    Let me know if you have any questions.

    Regards,

    Arash