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TPA2017D2: Output current increases at the same input signal level

Roy Hsu
Genius 9260 points
Part Number: TPA2017D2

Hi Team,

My customer found that the output current at the speaker terminal increases at the same input level. (The circled area in the waveform)

I will send you the schematic as well as the waveform via private mail.

The customer disabled the AGC so it might not related to that.

Please help look into this issue.

Thanks! 

Roy Hsu

  • 0
    TI__Mastermind 20085 points
    Hi Roy,

    That's right, if the input signal level is increased, so the output level should increase too. As the AGC is disabled, then the output signal won't be limited.
    I noticed some details. They are just using one input channel and an output channel, so they could use another mono audio amplifier in their application and the AGC pins are connected to Vdd, so Are you sure that they are not using the AGC?

    Best Regards
    José Luis Figueroa
    Audio Applications Engineer
  • 0 in reply to José Luis
    TI__Prodigy 725 points

    Hi Jose,

    The problem we would like to figure out here, is the output signal level increased while the input signal level DID NOT increase.

    Have you seen the situation in other cases? Please suggest what test/modification we could do to fix the problem.

    Thank you.

  • 0 in reply to user4773196
    TI__Mastermind 20085 points
    Hi,

    The schematic shows that the AGC1 and AGC2 pins are connected and this activates AGC, limiter, compression, and noise gate functions. Then, this explains the device's behavior. These pins should be tied to ground in order to deactivate the AGC.

    Best Regards
    José Luis Figueroa
    Audio Applications Engineer
  • 0 in reply to José Luis
    TI__Genius 9260 points

    Hi Jose,

    We reworked the board and tied AGC1 and AGC2 to ground. However, we still observed the same phenomenon shown in the waveform below.

    (CH2 = Input signal, CH4 = Output Voltage)

    Now, this issue happens randomly (about 4 of 20 as of now). The trickiest part is that, on the normal boards, the output voltage remains the same even when AGC is ENABLED.

    While on the abnormal board, the same issue would occur even if the AGC is disabled (as the above waveform shows).

    Another thing is that, the Vcc of TPA2017D2 is only turned on when there's audio input (a couple of ms ahead of the input signal).

    Do you think this could be a quality issue? 

    Thanks!

    Roy Hsu

  • 0 in reply to Roy Hsu
    TI__Mastermind 20085 points
    Hi Roy,

    This condition is not recommended. The TPA2017D2 should be turned on before sending an audio input. The start-up time of TPA2017D2 is 5ms after this time you should send the audio input.
    As I mentioned before, I recommend you using a mono audio amplifier if you are just using one output channel.

    Best Regards
    Jose Luis Figueroa
    Audio Applications Engineer