TAS2563: Chose Thermal Limit correctly

David Rohner

Part Number: TAS2563

Hello

I've got a question regarding the TAS2563 Characterization using PPC3:

You have to set the Thermal Limit parameter which is described as the difference between the maximum temperature of the speaker and the ambient temperature.

My speaker has a maximum temperature of 70°C.
Which temperature is used for the ambient temperature?
- Is the ambient temperature during characterization (in my case roomtemperature 25°C)
- Or is it the maximum amient temperature of the device i later use the speaker in. (in my case the
device is specified to run up to 65°C ambient temperature)

Thank you for your help and best regards
David

9 months ago

+1 Wenbin Li1 9 months ago

TI__Genius 9280 points

Hi David,

you should use the ambient temperature when you do the speaker characterization.

Br,

We bin

0 David Rohner 9 months ago in reply to Wenbin Li1

Prodigy 10 points

Thanks for your answer.

I still don't get how the thermal protection works in the system if the ambient temperature varies. Because there's only a delta temperature value specified in PPC3 characterization process.
Is the ambient temperature measured by the amplifier? Or does it has to be set manually on startup?

0 Ivan Salazar 9 months ago in reply to David Rohner

TI__Guru** 114635 points

Hi David,

The thermal protection will track the difference in temperature of the speaker regardless of if the source of heat; ambient temperature or heating due to current flow, both phenomena will translate into Re variation, which is what the device use for temperature tracking.

You must input the ambient temperature for the speaker characterization and calibration processes. The device is not able to measure ambient temp by itself.

Best regards,
-Ivan Salazar
Applications Engineer

0 David Rohner 8 months ago in reply to Ivan Salazar

Prodigy 10 points

Hi Ivan

Thanks, but if my device later starts in a different ambient temperature than at characterization lets say 40°C instead of 20°C, than there would still be a delta temperature of 50°C programmed and the amplifier would let the speaker heat up to 90°C instead of the limit 70°C.

Is there a way to set the ambient temperature and delta temperature in the device? Or how is this usually managed if the device is used in different ambient temperatures?

0 Shenghao Ding 8 months ago in reply to David Rohner

TI__Genius 17855 points

Hi Guy,

Our tuning expert will feedback you shortly today.

0 Peter Wu5 8 months ago

TI__Expert 6100 points

Hi David,

In this case, you can set the ambient temperature to 40C, Tmax in PPC3 set to 30C, so the actual temperature limit is still 70C, not 90C. Thanks

0 David Rohner 8 months ago in reply to Peter Wu5

Prodigy 10 points

Hi,

So if I'm understanding this right, best practice is to do the speaker characterization once, and then create different tuning snapshots with different thermal limits.
And load the snapshot according to the ambient temperature...?

Or is it better to have multiple speaker characterizations for different possible ambient temperatures.
Then load the according characterization on startup...?

+1 Peter Wu5 8 months ago in reply to David Rohner

TI__Expert 6100 points

Hi David,

When you did speaker characterization, the ambient temperature is according to the actual temperature of the environment the speaker is placed in, you need to fill in Tlimit in PPC3 characterization procedure, Tlimit=Tmax-Tambient. Tmax should be the actual maximum allowed temperature for the speaker coil. For speaker characterization, one time is enough, no need for multiple characterizations for different possible ambient temperatures. When you placed the speaker in a different ambient environment, the speaker Re will change accordingly, hence the algorithm will also know the updated ambient temperature accordingly based on speaker Re change.