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Original question:

LM4871: Turn on transient?

LM4871: POP sound at speaker when SHUTDOWN transit from High to Low logic.

DanS
Intellectual 390 points
Part Number: LM4871
Other Parts Discussed in Thread: TPA6211A1,

Hi,

When I switch on the amplifier from Shutdown to ON mode by switching the SHUTDOWN pin from high to low, there is a loud pop sound at the speaker.

From the waveform at Vo1 (pin5), there occurs a spike that causes the pop sound. I do not see the spike at Vo2. Anyone could advise what causes the spike and how to eliminate the pop sound?

Thanks. 

   

  • 0
    TI__Guru* 84915 points
    Hi, Dan,

    Our team will check this issue and they will answer as soon as possible.

    Best regards,
    Luis Fernando Rodríguez S.
  • 0
    TI__Guru** 102065 points
    Hi Dan,

    For best pop performance, it is recommended to use differential input.
    The single-ended input of this amp could contribute to cause pop. Any mismatch in impedance between the inputs affects pop performance, as well as the capacitor charging to bypass voltage.
    For best pop performance I would suggest to consider using newer devices, like TPA6211A1 which is a fully differential amplifier. It is a single differential amp, while LM4871 has two internal amplifiers to create the differential output from single-ended input.

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators