TPA3251: TPA3251: TPA3251 has a noise during powering up and down

Jude Ma

Prodigy 35 points

Part Number: TPA3251

There is a pop noise during powering up and down, the waveform as below:

Yellow: Speaker

Green: AMP_NRST

Output SE configuration.
Noise happens at all output channels.
Increase C-start capacitor with 0.82uF in parallel, there is no improvement and pop noise happens sometimes in powering down.

The schematic as below:

over 1 year ago

0 Wei Qiu over 1 year ago

TI__Expert 5570 points

Hi Jude Ma.

I'll reply you later.

BR.

Wei Qiu.

+1 Wei Qiu over 1 year ago in reply to Wei Qiu

TI__Expert 5570 points

Hi Jude Ma.

The yellow waveform is differential output signal? It seem that it superimposes audio components. Could you also help to gather the waveforms of idle condition(no audio input)?

Under normal conditions, there will be a DC blocking capacitor charging and discharging process during power-on and power-off in SE mode, so the POP sound of power-on and power-off cannot be avoided in SE mode. If you want to avoid it, you can use BTL mode.

BR.

Wei Qiu.

0 Jude Ma over 1 year ago in reply to Wei Qiu

Prodigy 35 points

Hi Wei Qiu,

The yellow waveform is SE output signal, the idle condition waveform (no audio signal input) as below:

Is it possible to reduce pop noise with the following proper circuitry around the inputs and outputs?

0 Wei Qiu over 1 year ago in reply to Jude Ma

TI__Expert 5570 points

Hi Jude Ma.

It seems that your audio input has some noise.

The schematic you mentioned may can be useful. When standby control pull down, A will be high and then the output caps will discharge through the triode instead of the speakers.

You can use a simple board to have a try.

BR.

Wei Qiu.

0 Jude Ma over 1 year ago in reply to Wei Qiu

Prodigy 35 points

Hi Wei Qiu,

Yes, the input noise is the floor noise.

Audio

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TPA3251: TPA3251: TPA3251 has a noise during powering up and down