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TAS2553: BD Modulation

Hao Wang14
Expert 4415 points
Part Number: TAS2553
Other Parts Discussed in Thread: TPA3130D2

Hi Team,

TAS2553 uses BD modulation at the output, however, the tested waveform between one input of the speaker and ground is only half of the sine wave as shown below:

However, the BD modulation is also in TPA3130. But the tested waveform between one input of the speaker and ground is the sine wave.

My questions are:

1. What's the difference of the BD modulation between TPA3130 and TAS2553?

2. Can you share the block diagram of TAS2553 BD modulation?

Thanks and Best Regards!

Hao

  • 0
    TI__Guru* 95335 points
    Hi Hao,

    The complete sinewave can be obtained if you take both OUT+ and OUT- signals and obtain the difference, like a differential load would do.
    This modulation scheme is used in our latest Class-D amps.

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators
  • 0 in reply to Ivan Salazar
    TI__Expert 4415 points

    Hi Ivan,

    I know we can get compete sine wave if differential signal is applied to the speaker. However, if the single ended signal ( such as OUT+ and GND) is applied, the speaker cannot work normally.

    My customer's application is special because they want the speaker can work with either differential signal or single ended signal. So TAS2553 cannot work.

    But another audio amplifier TPA3130D2  can work with either differential signal or single ended signal, it's different from TAS2553.

    But TPA3130D2 claims to have BD modulation, you also mention that TAS255x has BD modulation. Why the single ended signal of TPA3130D2  TPA3130D2 has complete sine wave while TAS255x cannot? I think the BD modulation in TPA3130D2 and TAS2553 may be not the same, I cannot find the description of TAS2553 BD modulation, so I cannot compare. 

    My questions are:

    1. What's the difference of the BD modulation between TPA3130 and TAS2553?

    2. Can you share the block diagram of TAS2553 BD modulation which can better help understand?

    Thanks and Best Regards!

    Hao

  • 0 in reply to Hao Wang14
    TI__Guru* 95335 points
    Hao,

    Sorry for the misunderstanding. TAS2553 (and most of our recent released devices) feature a modulation scheme known as ternary modulation. On this modulation half of the bridge is off during half period of the signal. This is implemented to reduce switching noise from the transistors.
    However, this modulation does not allow for single-ended speaker connection.

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