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Original question:

TAS2559: TAS2559 purepath console 3 tuning

TAS2559: Thermal Characterization Measurements in PPS3

Anthony Yoo68
Expert 1320 points
Part Number: TAS2559


Hi Ivan

Thank you very much for your answer to the previous question.
My customer has received the Learningboard2 EVM and is testing the Speaker Tuning.
But there was a problem with the Thermal Characterization measurement.
The temperature of the Voice Coil is set at about 40 degrees even after about 300 seconds. (It is too low.)
In addition, the Temperature Plot obtained from the simulation measurement is very different from the Temperature plot in the tuning guide document.
So my client think that the results obtained from the simulation measurement are incorrect.

I have some questions about this.

1.There is an item to enter a Temperature Coefficient. What characteristics of a speaker should this be put in?
The speaker manufacturer does not understand the meaning of this value.

2.What exactly does the value of the Controller Setting Correction (Default 10%) mean as shown below picture?


Fwhen I raised this to about 50%, What's the difference in the Thermal measurements?

3.What exactly does the Controller Gain value mean? In the tuning guide, it is recommended to write 0.01 for the 1W rated speaker and 0.03 for the 2,3W rated speaker.
Then, should I fill out 0.1 for a 10W rated speaker?

In addition, there are a few questions apart from the above.

4. Choose Your Speaker type has only Single Driver Closed Box. Is there only a single driver closed box to choose from?
Is there a way to choose a different option for another speaker?

Please Check it.

Thank you

Best Regards

From Anthony

  • 0
    TI__Guru** 110815 points
    Hi Anthony,

    Did customer input the correct values in the Safe Operating Area step? They should provide Excursion and Thermal limits.
    Regarding the Temperature Coefficient, the most important item would be the controller gain. As you have mentioned, if speaker power rate is higher, then controller gain needs to be increased.
    10W sounds like too high power rate, perhaps the speaker is too big and the device is not able to heat it. Have you verified that speaker model are correct in the Model Fit step? Did customer tried with a smaller speaker?
    So far only closed box speaker model is supported. In order to support different speaker like ported or passive radiator additional speaker models must be added to fit with the measurements. This is being supported in next-gen smart-amp generations.

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators
  • 0 in reply to Ivan Salazar
    Expert 1320 points

    Hi Ivan

    Thank you for your advice.

    I think that my customers have provided Excursion and Thermal Limits at reasonable values to suit speaker characteristics.

    Excursion: 0.28mm, Thermal Limits: 80 degrees

    How much control gain can be adjusted?

    Is there a way to change the value of another part?

    Please help me a little more.

    Thank you

    Best regards

    From Anthony.

  • 0 in reply to Anthony Yoo68
    TI__Guru** 110815 points
    Anthony,

    I'll double check on the controller gain.
    Can customer try with a smaller speaker? Perhaps speaker is too big that the driver cannot get it to heat.

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators
  • 0 in reply to Ivan Salazar
    TI__Guru** 110815 points
    Anthony,

    I have some additional information about the ability to heat up the speaker.
    As you may know already, each speaker has a specific resonance frequency where there is a peak in impedance, and after that peak then the inductance of the speaker increases the speaker impedance considerably. Micro-speaker inductance kicks-in at a higher frequency than bigger speakers. So it is most likely that the 10W rated speaker that your customer is using has a considerably larger impedance at high frequency than a regular micro-speaker.
    TAS2559 family was focused to drive micro-speakers, so the pilot tone used to heat up the speaker is around 15kHz. If the above is true, then the impedance of the big speaker that customer is using is the cause that the driver is not able to heat the speaker, because it cannot drive too much power due to large impedance.

    We're working on beta versions of PPC3 to reduce pilot tone frequency so that bigger speakers can be characterized. Can you provide an e-mail address so we can discuss this in further detail?

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