TPA3255: Single-Ended Output Noise

Josef Fesl

Part Number: TPA3255
Other Parts Discussed in Thread: PCM1681, OPA1644,

Hey folks

I designed an amplifier based on the TPA3255EVM. Basically everything works quite well(BTL, PBTL). But when using the amp in SE-mode I get a lot noise on the Output. It sounds like the basic outout noise but way louder than in BTL and PBTL mode.

Has anybody had similar problems and solved the issue?

Maybe you also should know that the input origins from PCM1681 DAC with an output filter based on OPA1644.

Thanks and all the best
Josef

over 4 years ago

0 Sam(MPAA) Zhang over 4 years ago

TI__Mastermind 19080 points

Hi Josef,

Could you post your schematic here?

Have you done some noise measurement with BTL/SE? 20k low-pass filter, A-weighted setting is preferred. And also an FFT plot on the noise floor in idle status will also be helpful. We need to understand more about the noise.

Thanks!

Regards,

Sam

0 Josef Fesl over 4 years ago in reply to Sam(MPAA) Zhang

Prodigy 50 points

Problem solved! Turns out that TPA3255 circuit is doing it´s job. The noise is coming from the OPA1644 filter circuit. I will have to focus on this issue.

Thanks anyway!

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TPA3255: Single-Ended Output Noise