Issue with TAS5717

Hi Charles,I'm working on it. Please be patient.Thanks. Reagrds,Will

Hi Will,

Thank you for the updates. If you need any more information please let me know.

Regards
Charles

Hi Will,

It has been 2 weeks i am waiting for a reply.

Regards
Charles

Hi Charles,

Sorry for my late reply.
I did experiment several times and used different EVMs to copy the issue you have, but I can't see the same situation as yours.

What's the humming hear like? is it like your music which is playing? or just noise?
When you drive it to full volume, the music stopped at a moment and then go playing? or it played brokenly?

Regards,
Will

Hi Will,

I am not facing this issue with the EVM kit. I am facing this issue in our own custom board. This humming noise is a constant noise and i feel like some noise from either supply or ground is creating this issue. The music will play normally but this humming noise will be there along with the music. Can you suggest me where i have to look first to start debugging the issue?I have provision to add ferrite beads in the 24V path to the power amplifier.

Please advise the test , so that we can corner the issue.

Another issue i am facing is related to volume. If i increase the volume to high level the PA is shutting down momentarily and coming back. The issue will go if i reduce the volume. I feel like the PA is going to thermal shutdown. What is your thought in this issue? 

Anticipating an early reply.

Regards
Charles

Hi Charles,

I would like to check the humming noise is caused by TAS5717 and its related circuit.

Is it possible to fly audio source(output of codec) to TAS5717EVM?

Regards,

Will

Hi WIll,

I have tried with EVM kit and everything works fine. The issue is happening in our custom board and we need your help to resolve it.

Regards
Charles

Hi Charles,

Could you use external audio source to TAS5717?

If it has humming noise, we can say it's caused by TAS5717 and related circuit.

Then we might need schematic and layout of customer's board to figure out what is the root cause.

Thank you

Regards,

Will

Hi Will,

I am working on this with Charles but we have still not solved the problem.  Could you please have a quick look at the cct diagram below and comment.  We use a 3W 4R driver.

Also, after initialisation, we find that the PA and inductors get extremely hot even without applying any signal...is this normal?

Many thanks,

Dalibor

Hi Dalibor,

When the device and inductors get hot, did you look at the output pins of the device? It sounds like there is no switching going on and perhaps just a DC level?

The corollary to the above is, is the output oscillating (on top of the actual switching waveform)? If so, this would cause heating of the device.

Grounding and board layout is tantamount; do your grounds all return to one place on the board, or are you using a plane?

Mike T.

Hi,

I have changed the the operating mode to BD and the heating issue seems to have largely gone and the PA is taking a more sensible amount of current.  However, my colleague Charles originally raised a point about the hissing noise coming from the amplifier, which is still there albeit to a much lesser degree.  The PA is connected to a VLSI audio processor via I2S bus so I took a snap shot of the I2S traces whilst I could observe the noise from speakers.

Everything seems as it should be so I measured the output from the amplifier on the right channel so these traces are + & - between the output pin and the inductor.  The red channel is the math channel.

There seems to be an offset between + & - traces so I am not sure if this could be causing the noise?

I also took a spectra of the acoustic noise...see below.  It seems spread below 4kHz and kind of varies in intensity.

Any ideas welcome.

Dalibor