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.
Enters the TAS5733L
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:
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:
As I ran out of space on top I had to put a few components on the bottom:
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!