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TPA3255: 200W @ 8Ohm Mono Speaker with TPA3255

Christopher Müller
Prodigy 80 points
Part Number: TPA3255
Other Parts Discussed in Thread: TAS5634

Which mode should I use?

PBTL Mode states it must have only 2-4 Ohms. Can I use it with 8 Ohms too?

Or is it better to use BTL stereo mode and leave one channel un-used?

Best regards

  • 0
    TI__Guru 52410 points

    Hi Christopher

         It's OK for you to use 8Ω load under PBTL Mode, but the problem is our device can't give out 200W power on this large resistance. 

         The maximum power our device can give out is depending on two factors: the load resistance and the PVDD voltage. The typical max PVDD voltage is 51V, and considering the voltage drop in the circuit, usually we consider the peak value of the output is 49V. So the RMS of the sine wave is 34.6V at most. If you use 8Ω as the load, only 150W can give out by our device, no matter you use the PBTL or BTL.

  • 0 in reply to Shadow He
    Prodigy 80 points

    Thanks for the answer.

    What would happen if I raise the voltage to 59 V ?

    If i substract the 2 V you proposed to get lost in the circuit i get 57 V output.

    40,3 V rms

    -> 203 Watts

    The datasheet states, that the device withstands up to 69 V. 

    If this is not a good approach, what would be the sugestion from TI to get 200 W Audio Power on 8 Ohms? 

    I am not fixed to use this part... I just need 200 W RMS @ 8 Ohm from a class D power amp.

    Best regards

  • 0 in reply to Christopher Müller
    TI__Mastermind 19080 points

    Hi,

    Operating the device beyond the recommended operating voltage may cause issue. 69V is the abs max range. On our datasheet, we have below descriptions,

    "Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
    only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended
    Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability."

    Could you tell us the THD+N target at 200W output? 

    Thanks!

    Regards,

    Sam

  • 0 in reply to Sam(MPAA) Zhang
    Prodigy 80 points

    Hello Sam, thanks for the answer.

    Our target should be  THD+N of 10% or less @ 200W.

    The systemdesign should be

    1x Symmetrical Input ->

    2x Single Ended Input ->    CODEC with miniDSP to EQ the signal    ->   200 W Class D-Amp

    Best regards

  • 0 in reply to Christopher Müller
    TI__Mastermind 19080 points

    Hi,

    You may take a look at TAS5634. It supports 230 W / 8 Ω BTL Stereo Configuration at 10% THD+N level.

    Just note that it accepts the PWM input. Thanks!

    Regards,

    Sam

  • 0 in reply to Sam(MPAA) Zhang
    Prodigy 80 points

    Hello Sam,

    thanks so much for the suggestion. This IC looks pretty good for our purpose.

    But we a a little confused which CODEC or ADC we could use for analog inputs and with embedded miniDSP and a PWM output.

    I cannot find any on the website. 

    Could you please give advice?

    Best regards

  • +1 in reply to Christopher Müller
    TI__Mastermind 19080 points

    Hi,

    For example, TLV320AIC3268 could be the choice. It also has integrated miniDSP to do the audio processing. And the output should be in "PCM", which could be go directly to TAS5634.

    Thanks!

    Regards,

    Sam

  • 0 in reply to Sam(MPAA) Zhang
    Prodigy 80 points

    Thanks... this helped me out. Didn´t know that PCM is the same as PWM in audio processing! 

  • 0 in reply to Sam(MPAA) Zhang
    Prodigy 80 points

    cite: "...And the output should be in "PCM", which could be go directly to TAS5634..."

    Is this statement really true? PCM is not the correct format to go into TAS5634 but TDM format is. 
    Could you please clarify?

  • 0 in reply to Christopher Müller
    TI__Mastermind 19080 points

    Hi,

    TAS5634 doesn't accept TDM signal. It accepts PWM(or PCM input).

    Thanks!

    Regards,

    Sam

  • 0 in reply to Sam(MPAA) Zhang
    Prodigy 80 points

    Thanks.

    Yes you are right... But I cannot find any information in the datasheet that the TAS5634 accepts PCM. 

    Where did you find that information?

    Best regards

  • 0 in reply to Christopher Müller
    TI__Mastermind 19080 points

    Hi,

    PCM is short for Pulse-code modulation. In this scenario, PCM and PWM are the same thing. Thanks!

    Regards,

    Sam

  • 0 in reply to Sam(MPAA) Zhang
    Prodigy 80 points

    Thanks for clarification.

    As Hardware Dev I am not so deep into that Software/Signal thing.

    But my customer wants me to use only parts to run in perfect specification. It is a well know big company in Germany and these are their rules. 

    As in the datasheet only stated PWM and not PCM this looks like we are running a part not made for the purpose with the amp chip.

    Because we feed PCM into PWM. And without the information that this is the completely same thing, to a person who is not deep into that audio thing it is confusing.

    And it is even more confusing from the online part-filter because you can filter for PWM or for PCM and get different results in parts from TI.

    Why TI does this, wenn PCM and PWM is the same?

    You guys should at least put into the datasheet of the TAS5634, that it also understands PCM. Maybe in that kind: Input: PWM/PCM or something.

    Thanks!

    Regards, Chris