Question about TPA3251d2 Output power and click/Pop noises

Bernhard Waechter

Hello,

I designed my TPA3251d2 based amplifier board and had the possibility to make the first tests in lab.

Basically it runs very very stable but there are two things I'm a bit worried about.

First is the output power. I did a test with 8 Ohms Load and a PowerSupply of 36V in BTL configuration. One channel driven. Setup is 100% identically to your evm board, except the Cstart = 100nF in my design.

For 10% THD+N the resulting power was 80W which is kinda far away from the datasheet which says almost 100W in fig. 8 on page11. Same with 4 Ohms load, I was not able to reach the given power from the datasheet.

Test Signal was 1kHz Sine out of my Rohde & Schwarz UPL Analyzer. I also did some math of the voltage and current across the load and the results of my analyzer were correct.

So how did you measure the power in datasheet? Was it also a sine signal?

Next Problem ist the click and pop noise on switch on and off. It's a really loud one and I'm kinda worried about the customers loudspeakers.

Is there a workaround for that?

Thanks in advance.

Best reagards

Bernhard

over 9 years ago

0 Mike Tripoli over 9 years ago

Genius 3295 points

Hi Bernhard,

Can't speak to the wattage measurements.

Regarding the click and pop; you saw in the data sheet it's recommended to hold RESET low during power down to mute the speakers?

Mike T.

0 Bernhard Waechter over 9 years ago in reply to Mike Tripoli

Intellectual 620 points

Hi Mike,

thanks for your fast reply. I fixed both Problems. Click/pop noise could be fixed with a simple circuit which monitors the supply voltage and resets the amp.

Output power issue was because of a failure in my preamp.

It's now working perfectly.

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Question about TPA3251d2 Output power and click/Pop noises