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DC bias and noise ouput of TAS2552EVM

Other Parts Discussed in Thread: TAS2552EVM

We have purchased several TAS2552EVM boards for audio testing. A DAQ card is used to acquire the sensed current and voltage signals. We found that there existed DC bias for v-sensed signal, and for different boards, the DC bias values are different. While for the i-sensed signal, the DC bias is quite small.

In the following figures, I-sense signal is showed at the top while V-sense signal at bottom

TAS2552EVM board No.1

TAS2552EVM board No.2

TAS2552EVM board No.3


Also, we found that the noise on the sensed signals is quite heavy for one of the TAS255EVMs compared to the other two, so we wonder why the TAS2552EVM boards behave differently?

TAS2552EVM board No.2

Another thing is that if a white noise signal which is high-passed with fc = 200Hz is fed to the TAS2552EVM digitally, noise below 200Hz appears at the ClassD ouput.

 

Many thanks!