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TPA3138D2: Using BTL input configuration (left + right) and 1SPW mode at the same time

Cameron Wutzke
Intellectual 2551 points
Part Number: TPA3138D2
Other Parts Discussed in Thread: PCM2704

Hi experts!

We realize that in BD Mode, the under-voltage protection is set at 7.5V. Since our circuit is powered only by the USB port, we must use the 1SPW mode (UVP = 3.4V).

 The problem we have with the 1SPW mode, is that we have only 1 input channel (left or right) at the same time. We don’t need a stereo output in our project, but we need to merge the left and right channels that come from a PCM2704.

 

On the TPA3138, is there a way to use the BTL input configuration (left + right) and the 1SPW mode at the same time?

If not, what is your recommendation to merge the left and right channels into a single channel, if we use the 1SPW mode? (resistors, op amp, audio transformer, IC, etc)

Thank you,

Cameron

  • 0
    TI__Mastermind 38020 points

    Hi Cameron

        BD and 1SPW mode in our device means different PWM switching mode, it has nothing to do with left channel and right channel.

        And about BTL, we means using 1 pcs 3138 to drive two speaker, left channel and right channel are separate. And PBTL is to use 1 pcs 3138 to drive only 1 speaker, and there's only one input signal channel.

        Our device won't be able to merge the left and right channels into a single channel, your choice about 2704 seems fine. BTL and 1SPW doesn't affect each other, you can use them together.

  • 0 in reply to Shadow He
    TI__Intellectual 2551 points

    Thank you! If I understand correctly, it is impossible to use BTL to drive only 1 speaker?

    In the future, if we must merge L + R audio channels, do you have recommendations how we could do this cheaply? Customer does not care about high audio quality.

  • 0 in reply to Cameron Wutzke
    TI__Mastermind 38020 points

    Hi Cameron

    Cameron Wutzke said:
    it is impossible to use BTL to drive only 1 speaker?

       You can, it means you only use one channel of 3138, leave another channel unconnected. Usually our customer will choose PBTL instead of such use.

       

    Cameron Wutzke said:
    In the future, if we must merge L + R audio channels, do you have recommendations how we could do this cheaply?

       Since they don't care about quality, how about use a simple Amplifier to add the two input signal together? Something like below picture.