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Original question:

TPA3138D2: schemactics review help

TPA3138D2: Inductor solution check on TPA3138D2 BTL mode

Jonathan Liu1
Prodigy 10 points
Part Number: TPA3138D2

Hi

We would like to design a inductor solution on TPA3138D2 BTL mode which the speaker is 4ohm or 8ohm.

After we calculation and verify on EVM board, the max watt we get are 6.5w at 8ohm/33uH/1uF and 9.5W at 4ohm/15uH/2.2uF if the output waveform is not distortion.

8Ohm(Vin=12V):

4ohm(Vin=12V), Tc=57 °C at room tempture 25°C:

Would you help check is this design OK? Because we want inplement this circuits on our new project next month.

  • 0
    TI__Mastermind 44715 points

    Hi Jonathan,

    We are assuming the max power you are calculating is the 1% THD, using the equation in section 9.3.3 of the datasheet.

    Pout= (((RL/(RL+2*Rs))*Vp)^2)/(2*RL)

    Vp=12V
    RL=4 or 8
    Rs= Rdson + Rdc(inductor);  0.18 + 0.1 = 0.28 ohms.  The Inductor DC resistance is an estimated value since it is not given in your post.

    4 ohm power calculation provides 14.8W at 1% THD
    8 ohm power calculation provides 8.1W at 1% THD