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TAS2563YBGEVM-DC: About speaker characteristics

Fumiya Sano
Prodigy 130 points
Part Number: TAS2563YBGEVM-DC


Tool/software:

Hello, some engineers.

We are evaluating the characteristics of the speakers used in our products using the PPC3 app via the TAS2563YBGEVM-DC.

Once the speaker characteristic evaluation is complete (although the final allowable temperature check has not actually been completed), you will see this screen.

I don't understand some of the parameters shown, so I'd like to ask what they are called and what they mean.

・Ke()

・Rtv(K/W)

・Ctv(J/K)

・Rtm(K/W)

・Ctm(J/K)

・Rtvs(K/W)

・SOA - System gain

Can you please explain the above parameters?

Regards,

Fumiya.

　

  • +1
    TI__Guru** 110745 points

    Hi Fumiya,

    You can refer to this document: SmartPA Speaker Protection Algorithm

    Best regards,
    -Ivan Salazar
    Applications Engineer

  • 0 in reply to Ivan Salazar
    Prodigy 130 points

    Hi, engineer.

    Sorry for marking this as "Resolved" once.

    The PDF I was provided contained information about Rtv, Ctv, Rtm, and Ctm.

    However, there was no information about Ke, Rtva, or SOA.

    ・Is Ke the same as the coefficient k in the PDF description? If so, I would like to know because there is no information about k. If not, I would like information about Ke.

    ・I think Rtva is a different parameter from Rtv. Can you tell me about this?

    ・Regarding SOA (System gain, Supply Voltage), I assume it is a general parameter, but I would appreciate it if you could let me know.

    Regards,

    Fumiya.

  • 0 in reply to Fumiya Sano
    TI__Guru** 110745 points

    Hi Fumiya,

    • Ke is temperature coefficient of resistance for copper, the usual material for voice coils.
    • The system gain is the amplifier analog gain, fixed for 16dBV in tuning mode; the value in the SOA block is the Vrms equivalent of 16dBV = 8.92Vrms.
    • I'll double check on Rtva and come back to you.

    Best regards,
    -Ivan Salazar
    Applications Engineer

  • 0 in reply to Ivan Salazar
    TI__Guru** 110745 points

    Hi Fumiya,

    • The difference between Rtv and Rtva is:
      • Rtv is thermal resistance for the dissipation going from voice coil to magnet (this then goes from magnet to ambient, Rtm).
      • Rtva is the thermal resistance for the dissipation going directly from voice coil to ambient.

    Best regards,
    -Ivan Salazar
    Applications Engineer

  • 0 in reply to Ivan Salazar
    Prodigy 130 points

    Hi, Ivan.

    Thank you for your answer.

    (1) I understood SOA.

    (2) Regarding Rtva, I have summarized my understanding in the first attached photo. (This is a modified version of Figure 12 in "SmartPA Speaker Protection Algorithm")
    Is this understanding correct?

    (3) I think the temperature coefficient of resistance of copper is the "Temperature conficient" shown in the second photo. In fact, the temperature coefficient of resistance of copper is 0.003 to 0.004, which is a reasonable value. On the other hand, Ke is a dimensionless coefficient of the inductance model, I personally expect it to be a coefficient related to a physical spring constant or electromotive force, etc.
    I'm quite puzzled because it's not listed in the TI documentation, and there are no similar parameters in the documentation for the speakers I'm using.

    I'm sorry, but I would appreciate it if you could answer to the best of your knowledge.

    Regards,

    Fumiya.

  • 0 in reply to Fumiya Sano
    TI__Guru** 110745 points

    Fumya,

    Sorry for the confusion, my description was indeed for K in the temperature block.

    Ke is part of the Inductance model; this is actually not used for the speaker protection and can be ignored for that purpose (same as Le and L2).

    Edit: you're correct on Rtva.

    Best regards,
    -Ivan Salazar
    Applications Engineer