TI’s class-D power amplifier solutions for high-end audio

Norman,

Those are pretty tough specifications to hit. I can't promise to hit everything with one part, but there is one particular part that comes to mind.

I'd have a look at the TAS563x devices. The TAS5630 is an analog input part, the '31 is a PWM input part.

THD is down around 0.03% (if memory serves) and output power is up to 600W (at 10% THD... well above 300W for 1%)

The easiest part to get into and prototype is the analog input part - the TAS5630.

My only concern is the the power bandwidth up to 100kHz. The '5630 with the standard LC filters we use on the output can handle up to 73kHz. I believe we can push a little higher as well, but all the way to 100kHz may cause the part to struggle.

Have a look at the datasheet, and let me know what you think.

Cheers, Dafydd

Hello Dafydd & Forum readers,

Thanks for the quick response last Thursday. I have reviewed the TAS563x devices and they do look promising for this application. I find it very clever how the TAS5630 analog input and TAS5631 digital input versions are pin compatible on 41 out of 44 pins on the DKD packages. I was disappointed the TAS5631 lacks an evaluation board. That is what led me to check the common pin outs between TAS5630 and TAS5631 and hatch the following scheme to quickly get an evaluation circuit online.

Hack the TAS5630DKD2 Evaluation Module by:

1.     Replace the TAS5630 with a TAS5631, account for the needs of pins 14, 15, & 16; and

2.     Break in to the INPUT_x nodes (pins 6, 7, 12, & 13) at the inline resistors between the TAS5630DKD2 board’s input op-amp stage and TAS5630 footprint. The analog input stage is thus disconnected from the TAS5630 footprint. We’ll use shorting pins on the analog input jacks to keep the abandoned in place op-amps quiet.

3.     Connector (to be determined matching front end to be selected) now connected to the TAS5630 footprint pins 6, 7, 12, & 13.

Now one has a TAS5631 equipped PCB ready to connect to a TI Digital Audio PWM Processor presumably from the TAS5xxx family. Using the ti.com select page for the Digital-Input PWM Controllers limiting to 192k Fs max for this application’s requirement nine devices are offered TAS5010, TAS5012, TAS5028, TAS5028A, TAS5086, TAS5504, TAS5504A, TAS5508B, and TAS5518. Among that list I would tend to short list the TAS5010 and TAS5012 because they are 2 channel outputs matching the specification and the TAS5518 because it is listed as having the highest dynamic range. Am I correct in noting all of their evaluation boards include power amp stages like the TAS5028-5122C6EVM? Is there a PWM Processor evaluation board minus the power amp stage one could use with the TAS5631?

I also spent time looking at the TAS3xxx audio processors. The TAS3108 looked great until I realized it lacks the PWM outputs needed for TAS5631. Looks like TAS3308 is the only one with PWM outs and it’s Fs maxs out at 48k, a deal killer. But it does have the TAS3308EVM a quite nice evaluation board.

Comments please, have I missed the PWM Processor that supports 192k inputs to PWM outs and has an evaluation board? Or is my application too niche and its time to design my own TAS501x to TAS5631 PCB?

Enough for now, regards,

Norman Tracy

ACG

Hi, Norman,

We are in the process of releasing a TAS5631 EVM that will contain a TAS5508 for PWM generation.

If you can wait, I suggest you do, fly wiring PWM signals can be a bit tricky...

I wouldn't suggest using the TAS501x devices, I don't think they will meet your audio requirements. They are quite old, and our newer devices have better performance. The pity is, you have to buy a multi-channel device for your stereo application. You may find the newer devices are cheaper, anyway.

-d2

Don, I have a 5630 EVM. I'm  very, very interested in '31 EVM. When might we see these and can you provide any advance info.  What will the board have for inputs (S/PDIF, analog etc) Will there be USB for the DSP control also?

Cheers...Doug

Doug,

The TAS5631 EVM is going thru the release process right now. I expect it will be available in a few weeks.

Attached is the preliminary users guide for it.

-d2