Class D audio amplifier using TPA3116 chip, high efficiency, high output power for its size

Design specification:

• Class D amplifier using TPA3116 IC
• 50W output (4Ω load) with 24V DC input power
• Adjustable gain and oscillation frequency
  • Gain from 0-40dB
  • 400kHz, 500kHz, 1000kHz and 1200kHz adjustable oscillation frequency
• Small and compact design (62×55mm)
• Bluetooth and auxiliary (3.5mm) input available

Design description:

This project is an update of a project which I built one year ago. I posted my original project on Chinese version of LCEDA and shared at OSHWHub. Throughout the time, I have updated the project to make the design more compact and useful. The original design can be found on this at Reference session. That was my very first PCB design, the improvement of design and layout can be seen on the picture below. The version of this project is V4.1, which is much more compact compared with my previous design.

Version 4.1 has all the function that is listed in the specification. I cut down the media keys but this can still be achieved by adding those on a extention board.

The final design of V4.1 looks like this:

There are some problems with the heat sink that is worth to note it down:

The heatsink on the picture is a 25×25mm aluminium heat sink. It has good thermal performance (temperature never exceed 50° on full power), but the size of the heatsink is a little bit too big. To solve this problem, I pushed two inductors in the middle a little bit backward to fit the heatsink in. Another alternative solution is to use a 20×25mm heatsink, which can fit perfectly and it works fine when the output is below 40W. 40W output can be pretty loud for indoor use, and I would recommend to use the alternative solution when it comes to the choice of heatsink.

Gain and oscillation frequency adjustment:

Gain can be adjusted by turning the potentiometer R3, the reference table is shown below:

The frequency adjustment is done by adjusting the connection on AM0, AM1 and AM2. Normally, there is nothing connected to these slot, which will give 400kHz of oscillation frequency. The frequency adjustment is shown on the table below: (1=connected with 0Ω resistor, 0=NC)

Reference links:

The project I built back in the day (V1.2) https://oshwhub.com/PotatoEngineDriver/dpoweramp

TPA3116 Datasheet: TPA3116D2 15-W, 30-W, 50-W Filter-Free Class-D Stereo Amplifier Family With AM Avoidance datasheet (Rev. G) (ti.com)