Project Update: TAS5733L Audio Amplifier

A little update

Following the past months’ trend I am not posting as often as I wish I could, but the project is alive and well.

One of the key functionality I want my ESP32 based project to have is sound. More specifically, I would like it to be a bluetooth speaker or an internet radio. The good news is that code to perform this already exists; courtesy of GitHub user MrBuddyCasino. Originally, for the sound amplifier I had bought a MAX98357 breakout from Adafruit as recommended; and it’s true it works pretty darn well. Hearing an internet stream through your ESP32 plugged into an amp for the first time is definitely a good feeling.

The downside is that it’s mono, 3W, and has no interface. Basically it’s good as a proof of concept amplifier but I doubt it’ll take me much further. Enters the TAS5733L.

The MAX98357A breakout from Adafruit: a good start but very limited
The MAX98357A breakout from Adafruit: a good start but very limited

 

 

Enters the TAS5733L

TAS5733L 0.5mm pitch next to a DIP8. Might be a bit of a soldering challenge!
TAS5733L 0.5mm pitch next to a DIP8. Might be a bit of a soldering challenge!

I did a LOT of research on a I2S audio amplifier and fell in love with the TAS5733L from Texas Instruments. Main features include:

  • Stereo amplifier
  • No MCLK signal required on I2S (the ESP32 can’t provide natively a MCLK signal).
  • 10W @ 12V into a 8Ω speaker, 16W into a 4Ω speaker.
  • Digital controls over I2C with volume and 3 band equalizer.
  • And on top of that it’s a package with legs –I hate soldering QFN by hand!

It’s absolutely amazing on paper, but it’s a really complex project on its own. The 48 pin package has a somewhat rather complex schematics:

TAS5733L basic stereo application
TAS5733L basic stereo application

 

Because of this complexity I decided to prototype the board before going any further.

 

TAS5733L: Making of a hobby level PCB

Texas Instruments recommend using multiple layers board, with a layout making use of very small resistors and capacitors. Needless to say these are good industrial advice, but not practical for a hobbyist like myself. I needed to contain this monster on 2 layer PCB, with components no smaller than 0805; while maintaining good thermal performances. A very challenging PCB with these new constraints indeed! Here is what I could come up with:

TAS5733L prototype board: top layer
TAS5733L prototype board: top layer

As I ran out of space on top I had to put a few components on the bottom:

TAS5733L prototype board: bottom layer
TAS5733L prototype board: bottom layer

 

Texas Instruments specifically indicates the place of C3 and C4 are of the utmost importance so I made sure they are right on the pins they are decoupling. At this point in time I am still waiting for the PCB to reach me so I have no idea how this design will perform. Soldering might prove itself a bit of a challenge: pin pitch is 0.5mm. As per usual: stay tuned!

 

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