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PCM1803: VREF Max Capacitance

Matthew N
Intellectual 1740 points
Part Number: PCM1803

E2E,

We have an issue where a pop is generated when the battery is quickly removed from my audio product that uses a PCM1803, and we noticed that it improves if we place more capacitance on VREF. 

The datasheet recommends a 10uF and a 0.1uF, but we are seeing a 100u in place of the 10u seems to help, but I wanted to know if there is any maximum capacitance values or any reasons we  could or should not put this amount of capacitance on those lines. Also, should the caps on Vref1 and Vref2 be balanced? Can you clarify how do those supplies interact?

Best regards,

Matt

 

  • 0
    TI__Guru* 84915 points
    Hi, Matthew,

    The audio converters are sensitive to voltage changes in the power supply pins. Normally, the pop issues are related to voltage changes in the power pins or in the analog inputs/outputs. So, the recommended capacitors are used to have a stable voltage at the power supplies. Even if the battery is removed, the high capacitors would avoid a high voltage change. They will be slowly discharged and the pop will be avoided. There's no a maximum capacitance value for the power supplies. So, 100uF (or more) capacitor could be a good solution. There's no a direct interaction between both Vref1 and Vref2 pins.

    Best regards,
    Luis Fernando Rodríguez S.
  • 0 in reply to Luis Fernando Rodriguez S.
    TI__Intellectual 1740 points
    Thanks Luis. Greatly appreciate the help!