TAS2781EVM: TAS2781RYYR support

Hi Richard,

if the output level is low this can often be caused by incorrect speaker characterization data. 

Has the speaker TS parameters been updated to match the speaker? either the TS parameters from the speaker vendor or the values found from speaker characterization. the speaker resistance 'Re' is important in the speaker protection algorithm.

speaker characterization can be performed either with Klippel test equipment or with TAS2781EVM + SALB2 PP-SALB2-EVM Evaluation board | TI.com

If your team does not have the SALB2 we will be soon releasing a new PPC3 version which will not require this hardware which we expect to release in this month

Regards

Arthur

Hi Aruthur,

I work with Richard at Impulse Labs.

We now have both the TAS2781 EVM and the PP-SALB2-EVM.

For background; we are trying to drive a transducer that is bonded to the glass of our cooktop with TAS2781.

We do get sound out of the TAS2781 out of the setup in bypass mode.   It is much less than what we get for the same power with a cone speaker, but that's to be expected.

I believe I have PPC3 working OK as I can get a fitted IV curve with a bookshelf speaker that I tried.

But I get 'fit failed' when I repeat the same process with the transducer   

One odd thing I noticed was that I do not see a bias voltage on the Dayton electret microphone that TI supplied with the kit.

Thank you,

-- Christopher.

Hi Chris,

No issues with the schematic it all looks good,

regarding your impedance fit failing it looks like the Glass+Transducer do not have a meaning full resonance frequency like a traditional speaker. the algorithm will need this to properly fir. 

This portion of the characterization is used for the speaker model used for excursion protection. correct me if im wrong, but i don't believe you are concerned about large displacement of the cooktop causing damage. 

If that is the case we can simply enter some spoof values for the F0/Q. and all we will be concerned about is the speakers Re and the thermal protection. I can create some spoof values which will never engage the excursion protection on my side, and you can pick up the characterization at the thermal protection step. 

I will provide this tomorrow

Regards,
Arthur

you are correct.  we do not care about excursions.

thank you so much.