TPA3255: Dead time on TPA3255

user5327551

Part Number: TPA3255

I have read all the documents of TPA3255 including the PFFB SLA.

I am aware of the THD+N (with or whiteout PFFB) but THD is influenced a lot by inductors and capacitors . My question is , the lowest THD (not influenced by LC filter) depends on the dead time on/off at mosfest.

Can you tell me whats the measure of that time on TPA3255 (in ns).I think its around 15ns ?

over 5 years ago

0 Robert Clifton56 over 5 years ago

TI__Mastermind 27530 points

Hi user5327551,

You really know your class-D architecture. While dead time is important, slew rate also greatly affects the THD+N in the device, and the general noise floor/amplification of that noise.

I will have to check with the design team to confirm this question. But may I ask why you want to know the dead time? This isn't a parameter that you can control in this device. What are you ultimately trying to accomplish in your system? Perhaps I could help.

Best Regards,

Robert Clifton

0 user5327551 over 5 years ago in reply to Robert Clifton56

Intellectual 830 points

Hi Robert

we are designing an inductor for this unit and we want to know if its worth it or not. What is the lowest THD that this amp can output depends on dead on time. Depending on that we will look at designing a specific inductor with a specific core/material and will try to get very close to the theoretical fllor

Right now I am guessing it has 10-12ns

0 Robert Clifton56 over 5 years ago in reply to user5327551

TI__Mastermind 27530 points

Hi user5327551,

Thanks for sharing. I've asked the designer to take a look at the specs and hopefully will be able to provide you an answer within the next couple of days.

Best Regards,

Robert Clifton

0 user5327551 over 5 years ago in reply to Robert Clifton56

Intellectual 830 points

Any update ?

0 Robert Clifton56 over 5 years ago in reply to user5327551

TI__Mastermind 27530 points

Hi user5327551,

Took a while to figure out this. Since it's not in the datasheet I can't explicitly say what the dead time is on our devices.

I will say that your approximation is close. But that's all I can share.

Very sorry I can't provide any more details.

Regards,

Robert Clifton

Audio

Audio forum

TPA3255: Dead time on TPA3255