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Question about TPA2005D1

Joel Loucord
Prodigy 20 points
Other Parts Discussed in Thread: TPA2005D1

Hello,

I would have your comment about the use or the behavior of the TPA2005D1.

My test configuration is the following: a MCU generates 2 differents PWM audio signals (150KHz PWM frequency), each one applied to a 1µF-150KOhms RC network (decoupling capacitor in series with gain resistor) connected to each IN- and IN+ inputs pins. A speaker connected between VO+ and VO- finally gives the mixed audio signals.

As you can see I'm not using any RC low-pass filter to smooth the PWM signals before application to the audio amplifier, but the TPA2005D1 works well. If I insert a RC low-pass filter (Fc < 20KHz), I just got a sound a little bit noisy (with a sound quality enough for my application).

I'm finally surprised to see that the LPF is not mandatory, and that the TPA2005D1 finally behaves normally.

Is this configuration of use finally acceptable, or do you see any possible drawbacks or risks ?

I greatly thank you for your answer.

Best regards,

Joël

 

 

 

 

 

 

 

  • 0
    TI__Guru**** 189401 points

    Hi, Joel,

    Welcome to e2e, and thanks for your interest in our products!

    Do you have a way to measure THD? I would expect the THD to be higher without the RC LPF. Since the input of our device is designed to handle audio-frequency signals, sometimes we see problems with the slew rate of high frequency PWM signals.

    But, if you don't see this, then I guess it's ok in your application.

    I suspect the reason to get noise with the RC LPF is the grounding.

    -d2

  • 0 in reply to Don Dapkus
    Prodigy 20 points

    Hello Don,

    Thanks a lot for your fast answer ! You're great !

    Unfortunately, I don't have for the moment a way to measure the THD.

    I made a mistake in my first message: when I insert the RC filter, I get less noise (I mean a kind of white noise), which must be normal since the harmonics of the PWM frequency are better attenuated.

    As you said, since it's seems ok for the application, I will continue without RC filter.

    Best Regards,

    Joël