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Original question:

TPA3113D2: TPA3113 collocation 4 Ω 5 w speakers, use for a long time will lead to a loudspeaker distortion or damage

TPA3113D2: Max Ouput Power and PLIMIT Value Calculation

Jerry Yang
Prodigy 20 points
Part Number: TPA3113D2

Hi TI team,

After reviewing the discussion on the figure shown below, I still got some questions which confused me:

  1.  Just a double confirm, if Vin=1Vrms then after a 20dB amp it will turn up to 10Vrms (28.3Vpp)?
  2.  As PLIMIT=1.76V, the output voltage clipped at +/-7.04V then why is the output Vp-p = 15V shown in the table 2, am I misunderstood anything?
  3.  Currently, our designed Vin=250~750mV/ PVCC=12V/ RL=8ohm/ PLIMIT=1.8V/ Gain=20dB, could TPA3113D2 fulfill the 5W output to the speaker? Should I adjust the PLIMIT voltage and what is the minimum input for 5W output? (Please refer to our schematics as below.) 

5086.Audio.pdf

  • 0
    TI__Mastermind 19840 points

    Hi,

    The PLIMIT feature is for Vpeak of output, it can not limit output power, because the output may be clipped if input level is high, and output peak value exceed PVDD.

    For the table, 1Vrms, 20dB Gain setting, the Vpeak has exceed PVDD=12V.

    And the calculation for Pout in datasheet is for unclipped power, that means the Vpeak can not exceed PVDD.

    PLIMIT can not limit power, it only can limit Vpeak value. So you should limit audio input to prevent clipping.

    Regards,

    Derek

  • 0 in reply to Yanming Gong
    Prodigy 20 points

    From my understanding:

    1. 1Vrms 20dB gain setting will lead to 10Vrms (28.8Vpp) output and PLIMIT=1.76V will limit the Vpeak @ 17.04V. However, Vpeak has already exceed PVDD=12V so the output voltage will be clipped at 12V, am I right?

    2. From the calculation above, how come the Vp-p=15V and Pmax=5W?

    3. Any comment of my question 3?

  • +1 in reply to Jerry Yang
    TI__Mastermind 19840 points

    Hi,

    Q1: Correct.

    Q2: Vpeak=12V, and the calculaed Vp-p value is 16.97V. However, the internal Rdson and inductor, trace have loss, so the in fact measured output is 15V Vp-p.

    Q3: 5W/8ohm application, if you want to unclipped 5W output, the Vp is 8.95V. So the Plimit voltage is 8.95/4=2.24V. The max Vin is 8.95/1.414/10=0.633V(Rms)

    Regards,

    Derek

  • 0 in reply to Yanming Gong
    Prodigy 20 points

    Hi Derek,

    That's clear for me, thanks for your prompt response.

    BRs,

    Jerry