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TPA3120D2 data sheet misleading

Vic Elias
Prodigy 110 points
Other Parts Discussed in Thread: TPA3120D2

Why does the datasheet headline "advanced power-off pop reduction" yet doesn't tell you that a bunch of extra circuitry is needed for this?  The data sheet doesn't show the extra circuitry needed which is shown in the evaluation module for it.  We missed the EVM stuff and designed this part in with terrible results.  Now we find the EVM schematic with all this extra circuitry to reduce the pop noise.

Why isn't any of this circuitry mentioned in the data sheet?  It's misleading advertising.

I also don't like the huge mute delay problem with the chip. 

 

 

 

 

 

  • 0
    TI__Guru**** 189399 points

    Vic,

    I am sorry to hear of the trouble our device is causing you.

    The TPA312x family incorporated some circuitry to control the duty cycle of the outputs when cycling in and out of shutdown. Basically, the duty cycle is slowly ramped from 0% duty cycle to 50% duty cycle at power up. Once this ramp is completed, then the audio signal is applied. This is the delay that you see in the d/s. The same thing happens when you put the device into shutdown. It's been a while since I listened to this pop, but I recall it being pretty good. Single-ended is always tough to fix the pop since the dc bias has to go from ground to mid-rail.

    The circuitry on the EVM is there to handle sort of a special case. That circuitry is there to handle pop when the power supply is removed. In this case, the external circuitry helps to more quickly discharge the bypass capacitor which is used as a timing element for the duty cycle ramp period.

    I will make a note in our system to address this the next time we update this data sheet so others are not caught off-guard by this issue.

    In your system, are you experiencing pop using the shutdown terminal, or when the power supply is removed? 

    Also, TPA3120D2 is NRND. You are not actually using the TPA3120D2, are you?

    -d2