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TAS5806MD: IC temperature in realtion to PVDD and outputfilter design

Severin Getzner
Prodigy 220 points
Part Number: TAS5806MD

Hello,

while evaluating my design, I experienced that up to 18V it is okay to drive the PMT-37N28AL01-04 speaker with ferrite bead output filters. Though I am not able to drive the IC with 24V, because it would then develope too much heat. Would LC-filters increase the performance regarding thermals, or is it simply the low impedance of the speaker?
Is there any setting in the IC that I could change in order to increase thermal performance? If not, is there an IC with built in DSP that could handle my use case better?

Use case:
Ferrite Bead output filter (lowest possible footprint)
24 V PVDD
5 W RMS and 10-15 W max per channel
4 Ohm DC resistance speaker
4 Layer PCB


  • 0
    Prodigy 220 points

    Also, how much power (1%THD+N) can the TAS5806MD output with the usecase from above but with PVDD = 12 V ?

  • 0 in reply to Severin Getzner
    TI__Genius 13360 points

    Hi Severin

    if using PVDD = 24v, 4ohm, your maximum current may go to 6A. that's such a high current, i think you can change to an ferrite bead with higher rated current.

    About the output power with PVDD = 12v, theoretically your max output power is about 18w.

    But considering other facts, the max power should be less than 18w.

    About the THD, for the LC filter affect a lot about the value, and we don't have the data when using ferrite bead.

    it would be better using the actual circuit to confirm the output power.

    thanks.

    Jesse

  • 0 in reply to Jesse Ji
    Prodigy 220 points

    Hey Jesse,
    well lets assume at 12V PVDD it can prdouce of around 85% of the theoretical 18W it would then be around 15W which is perfect. At 15 W outputpower and 4 ohm impedance at minimum, the current on the outputs would then be sqrt(15/4)=1.94 A. If I didn't make any mistakes, I assume that in this case the 3.1A ferrite bead should be sufficient. Please correct me if I am wrong, thanks.

    Severin

  • 0 in reply to Severin Getzner
    TI__Genius 13360 points

    Hi Severin

    your calculation is right, but the ripple current should also be considered.

    So I think take a measurement about the current would be better to confirm whether it has problem.

    you can connect a current probe between output pin and ferrite bead, then the ripple current can also be checked.

    thanks.

    Jesse