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TPA3138D2: Using BTL amplifier for SE outputs for cost savings

Nathan Olivares
Prodigy 30 points
Part Number: TPA3138D2
Other Parts Discussed in Thread: TPA3136D2, TPA3124D2, TPA3123D2

I've been working with the TPA3136D2/TPA3138D2 in its BTL configuration, but to be backwards compatible we will need to switch over to single ended outputs. Our power requirements are only ~2W to 8 ohm speakers given a single 12V power supply, so the losses from going BTL to SE shouldn't be an issue.

The best fit TI amplifiers I've found for this scenario are the TPA3124D2/TPA3123D2 which have native single-ended outputs, but these amps cost an order of magnitude more than the BTL amps ($350/1000 vs $3000/1000) for what looks like the same SE performance. 

Are there any problems I would face with using only the positive h-bridge outputs for each channel on the BTL amps? If not, how should the negative h-bridges be terminated and what should the altered circuit look like? Will I risk damaging my current TPA3136D2 board by connecting LSpeaker+ to OUTPL and LSpeaker- to GND to test the SE power output? If there are problems with using these/similar BTL amps in SE configurations, are there any other amplifiers you could recommend that are closer priced to the TPA3138D2 that would work?

Thanks

  • 0
    TI__Genius 9995 points

    Hi Olivares,

    As to your requirements, TPA3238D2 is the best chose on my side.

    It is suggested to use BTL configuration rather than SE considering pop performance. Further, if se output configuration is used, a large cap with current capability is also needed. 

    Can you check whether BTL can be used?

    BR

    Alix Wan. 

  • 0 in reply to Alix Wan
    Prodigy 30 points

    Alix,

    You mean the TPA3138D2, right? And it is impossible to use BTL as the intermediary board has two of the four audio traces tied to ground. We may make an additional board using BTL that would have to be installed separately, but the SE solution is still required.

    Do you have any capacitor recommendations and/or advice to guide me to choosing one for this setting? I've attached what I'm assuming will be necessary, but I feel like its missing something.




    Thanks,

  • 0 in reply to Nathan Olivares
    TI__Mastermind 19010 points

    Hi Olivares,

    As Alix talked, using SE configuration will lead pop issue, and it also bring EMI issue.

    The function is fine, and it can not damage device. But does customer can accept EMI and pop issues?

    I should suggest they can evaluate it firstly.

    Derek,

    Regards 

  • 0 in reply to Yanming Gong
    Prodigy 30 points

    Derek,

    How would this configuration cause pop issues, and couldn't I further filter the negative outputs to get rid of any noise?

    With these issues, would you then recommend to use the TPA3124D2 with its native SE output instead at 3x the cost?

    Thanks,

    Nathan

  • 0 in reply to Nathan Olivares
    TI__Mastermind 19010 points

    Hi Nathan,

    The pop is related to the output mismatch. In fact, we do not recommend to configure SE output. If customer want to use SE output, I suggest they can evaluate performance firstly.

    Regards,

    Derek