TPA3255 board output 450kHz at idle

[tempoct]

Hi,
I've just got an oscilloscope and testing amps around the house. A TPA3255 board (Chinese's wuzhi audio ZK3002) outputs its pwm at idle on both channels...(BTL mode). How can I get rid of it? Add more filters??
AP

 

[JonSnell Electronic]

Why do you want to get rid of something that does not matter as it is dissipated within the speaker system and totally inaudible.

 

[Nisbeth]

Looks like it is only around 0.5V?

 

[NIXIE62]

Shouldn't that remove the output LC filter?

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[russc]

It's got a fever!

 

[gberchin]

Is that open-circuit or with speaker load attached?

 

[Solve]

450 kHz is typical TPA3255
https://www.ti.com/lit/ds/slasea8a/...97502&ref_url=https%3A%2F%2Fwww.google.com%2F

 

[Solve]

Just forget it.

 

[Solve]

It's the switching frequency that TPA3255 have.

 

[tempoct]

First time using the 3255 here.

It is not open circuit, load (speakers) are connected. I understand that it is typical PWM frequency of TPA3255 that uses in class D. However, I thought output LC filter should get rid of it. I've just worry that it might fry the tweeter if something went more wrong....

 

[Extreme_Boky]

... why the heck would you ever use the noise generators (inside the amplifier AND inside the SMPS) in the audio chain..?? That HF rubbish will affect the phase noise response of the crystal oscillators inside the digital audio devices... forget about ever achieving the natural sound of the musical instruments.

... unless you want a Watt for a cent... 100Watts - 100cents.

 

[abraxalito]

It is not open circuit, load (speakers) are connected. I understand that it is typical PWM frequency of TPA3255 that uses in class D. However, I thought output LC filter should get rid of it. I've just worry that it might fry the tweeter if something went more wrong....

Your 'scope is showing 1.4Vp-p which is about 0.5VRMS. Into a 4ohm tweeter that'd be 63mW if the tweeter were purely resistive (its inductive actually so even less dissipation). Definitely nothing to worry about.

 

[ICG]

Into a 4ohm tweeter that'd be 63mW if the tweeter were purely resistive (its inductive actually so even less dissipation).

There are actually tweeters which don't have coil, magnetostats, air motion transformers ie have flat impedance and piezos are even capacitance like. The former ones might not be relevant but piezos might start oscillating of the amp.