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TPA3008D2: Shutdown pin for mute function (has big audio noise)

KJ Liu
Intellectual 530 points
Part Number: TPA3008D2

Hi Sir,

We have put the TPA3008D2 in our board  , the function looks fine. except one issue, we controlled the Mute/ un-mute through Shutdown pin (Mcu will sent a pull low or high signal to Shutdown pin) but there is always a big audio noise when we change the state. do you have any suggestion on it , 

  • 0
    TI__Expert 6985 points
    Hello! Shawn can help you further on your questions, but I also have a question for you. The TPA3008 is an older device and so have you looked at the TPA3136: www.ti.com/.../tpa3136d2 This is a new 10-W Stereo (BTL) Class-D Audio Amplifier that is also Inductor Free at these power levels while also offering Ultra Low EMI / noise performance which then saves you on the total BOM. Could this be a good option for you? Thanks, Jeff
  • 0
    TI__Mastermind 24835 points
    Hi KJ,
    Are you using single-ended or differential mode input please? With single-ended input mode, the pop noise could be high. The unused input should be ac grounded at the audio source instead of at the device input for best noise performance. If differential mode input is used, you need to take care of the matching of the differential input. Any mismatch on input routing could cause the common voltage difference on the input, and then cause pop noise on the output. BTW, PVCC is still on during mute/unmute operation, right? For the best power-off pop performance, need to place the amplifier in the shutdown mode prior to removing the power supply voltage.
    How much is the input capacitors in your design. It shouldn't be larger than 1uF. Please try to use a lower value for them and see if there is any improvement in pop noise.
    Best regards,
    Shawn Zheng
  • 0 in reply to Shawn Zheng
    Intellectual 530 points

    Hi Shawn,

    I am using differential mode and yes , you are right , the PVCC is still on during mute/unmute operation. I am not quite understand (need to place the amplifier in the shutdown mode prior to removing the power supply voltage.) could you please help to give more detail.

    the input capacitor  0.1uF and I can use lower value to test it .thanks you!

  • 0 in reply to KJ Liu
    TI__Mastermind 24835 points
    Hi KJ,
    'need to place the amplifier in the shutdown mode prior to removing the power supply voltage' means that when power off the device, you need to put it into shut-down mode first, then remove the PVCC. Else, a pop noise could be heard.
    Please also check the matching on the differential input.
    Best regards,
    Shawn Zheng