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TPA2012D2: output power at 3.3V

WONHO KIM
Prodigy 120 points
Part Number: TPA2012D2

Hi, 

I can see the various output power with different VDD from Figure 33. Output Power vs Load Resistance.

but i need to estimate the outpower power level at 3.3V to insure output power from TPA2012 is not bigger than 0.7W speaker. 

my speaker has 0.7watt rating thus i want to feed less than 0.7W to prevent blowing speaker. 

where i can find the equation to calculate?

  • 0
    TI__Guru* 95285 points

    Hi Wonho,

    What is the impedance of your speaker?
    The output power can be adjusted by changing the gain of the amplifier, or adjusting the input signal.

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

  • 0 in reply to Ivan Salazar
    Prodigy 120 points

    Hi, Ivan

    My speaker has 8 ohms. 

    And, I want to set the highest gain (G0.G1=0) and insure output power from TPA2012D2 is not more than 0.7Watt by limitation of VDD.

    is three any formulation to calculate this?

    I think I am asking the same question twice. 

  • 0 in reply to WONHO KIM
    TI__Guru* 95285 points

    Wonho,

    If you limit the output power by reducing VDD the output will be distorted. By lowering VDD the output signal will be clipped, if the gain is high the amplifier will still try to output the amplified signal, but if there is not enough voltage on VDD the signal at the output will be saturated.

    I would recommend to either test your maximum input signal across different gain levels to verify that 0.7W is not surpassed, or adjust the input signal amplitude on a specific gain level. These two options would help to not saturate the output signal.

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

  • 0 in reply to Ivan Salazar
    Prodigy 120 points

    Hi, Ivan

    what I wanted is how to calculate the maximum output power with 3.3V.

    if you can not answer this question then please stop replying. 

    I asked "A" but you are answering "B".

  • 0 in reply to WONHO KIM
    TI__Guru* 95285 points

    VDD = 3.3V and gain = 24dB:

    • Pout = 472.5mW into 8ohms @THD+N = 1%.Input = sine 128mVrms
    • Pout = 573.9mW into 8ohms @THD+N = 10%.Input = sine 152mVrms

    Below is a THD+N vs Pout plot for your reference.

    You can calculate the output power like any other Class-D amplifier, and you can also use the TINA model to simulate the device on your required setup. 

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

  • 0 in reply to Ivan Salazar
    Prodigy 120 points

    OK, thank you

    thus anyway less than 600mW in worst case, is that correct?

  • 0 in reply to WONHO KIM
    TI__Guru* 95285 points

    That is correct, for you specific VDD and load impedance conditions.
    Keep in mind that the input signal should be less than 152mVrms to keep distortion below 10% at gain = 24dB.

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