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TAS5421QPWP*Q1: Constant Hiss Noise

Srinivasa Narayanaswamy
Prodigy 30 points

The hissing noise is heard continuously from the speaker though no audio source is played.

Attached is the schematics design.

  • 0
    TI__Expert 5670 points

    Hi, Srinivasa.

    I think you can consider this question by following steps:

    1. Can you set the MUTE pin High or STANDBY pin low, and then observe if there have the same problem? If the problem still exists, this may not the chip's problem.
    2. If the problem disappeared after the operation above, you can replace the speaker with a resistor. Then can you observe the waveforms of input(the differential voltage between IN_P and IN_N) and the voltage across the resistor , and confirm if there is no input or disturbance? If convenient, can you post the waveforms to us?
    3. Another question is that the connection method of your audio input circuit is not very common, can you make a briefly explain? I suggest you to modify to our recommended circuit in the datasheet.

    Best regards

    Wei Qiu

  • 0 in reply to Wei Qiu
    Prodigy 30 points

    Can you set the MUTE pin High or STANDBY pin low, and then observe if there have the same problem? If the problem still exists, this may not the chip's problem.

    Srinivasa::After setting the STANDBY pin low, the hissing noise is not observed.

    If the problem disappeared after the operation above, you can replace the speaker with a resistor. Then can you observe the waveforms of input(the differential voltage between IN_P and IN_N) and the voltage across the resistor , and confirm if there is no input or disturbance? If convenient, can you post the waveforms to us?

    Srinivasa:: OK, will try this and share the results.Another question is that the connection method of your audio input circuit is not very common, can you make a briefly explain? I suggest you to modify to our recommended circuit in the datasheet.

    Srinivasa:: I am awaiting an answer from the HW expert, I  will update once I receive the answer.

  • 0 in reply to Srinivasa Narayanaswamy
    Prodigy 30 points

    Can you set the MUTE pin High or STANDBY pin low, and then observe if there have the same problem? If the problem still exists, this may not the chip's problem.

    Srinivasa::After setting the STANDBY pin low, the hissing noise is not observed.

    If the problem disappeared after the operation above, you can replace the speaker with a resistor. Then can you observe the waveforms of input(the differential voltage between IN_P and IN_N) and the voltage across the resistor , and confirm if there is no input or disturbance? If convenient, can you post the waveforms to us?

    Srinivasa:: OK, will try this and share the results.

    Another question is that the connection method of your audio input circuit is not very common, can you make a briefly explain? I suggest you to modify to our recommended circuit in the datasheet.

    Srinivasa:: I am awaiting an answer from the HW expert, I  will update once I receive the answer.