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TPA3255: Two TPA3255 in parallel

Darren Jenkins
Genius 10516 points
Part Number: TPA3255

Audio team,

I have a couple questions on the TPA3255.

Is it possible to parallel 2 TPA3255 with both in PBTL mode to drive a lower impedance load than 1.7 ohm?  I found two e2e threads that seemed to say different things.

https://e2e.ti.com/support/audio-group/audio/f/audio-forum/780849/tpa3255-can-multiple-tpa3255-used-in-parallel

https://e2e.ti.com/support/audio-group/audio/f/audio-forum/903238/tpa3255-tpa3255-output-power-improvement/3342837

If driving a low impedance load, mostly capacitive, the customer is saying the LC response can drop prematurely in frequency, as opposed to a resistive load.  Will connecting Post -Filter Feedback help correct the frequency response?

Thanks,
Darren

  • 0
    TI__Genius 9140 points

    Hello Darren,

    They just answer from different aspect. just simply parallel them together is not supported, as the output PWM are not synchronized, so any phase shift between two device will lead to pin-pin short when one pin drives high, another pin drives low. (this is the reason why 1st post says no doesn't support).

    While if it is parallel together after the LC filter, the story changes. (this is what 2nd post said).   Parallel them after LC filter will makes sure there is only audio frequency (PWM frequency level is attenuated by LC filter, and the energy left is very low). Still the precondition is: make sure audio input are exactly the same level and phase, otherwise the short will also happen.

    Dylan