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10W Class-D Stereo TPA3125D2 based Protoboard Amplifier Build Leave a comment
Built an amplifier based on a TPA3125D2. This is one of the few variants of DIP class-D packages TI offers. I’ve had one of them laying around for a long time that I never got around to putting to use and needed an amplifier on the side for a university lab project (lab TA recommended an LM386) so naturally this fit the bill.
I initially tried to build this on a breadboard but it turns out the high-frequency PWM-like nature of class-D amps doesn’t like the breadboard very much, so I moved to a protoboard instead!
I tried to follow all the PCB layout recommendations in the datasheet as closely as I could on the protoboard. Power traces on the bottom are all solid core copper, as well as amp outputs. The copper going over the IC was my solution to getting ground on the other side of the chip since the bottom of the protoboard was getting messy.
I designed initially for bridge-tied-load configuration for my lab project but later converted it to stereo single-ended. In both cases, cutoff frequency of the output filter was (very approximately) set to 20Hz into an 8ohm load. I tried to use what I already had on hand, so fancy X7R caps with 50V ratings didn’t make it into the design. The capacitors laying down were done to keep everything as close together as possible.
Still, it sounds pretty great for what it is! I feed it 15V using a USB-C PD to DC module off eBay which works great. Efficiency is awesome, the IC stays cool to the touch at a normal listening level. Would highly recommend this to people looking for a little amplifier project, especially since the datasheet is very detailed in terms of how to go about the design. I also had many bridged connections throughout building/testing that made the chip make all sorts of nasty sounds but wasn’t able to kill it in the process, the protection built-in is very good especially when coupled with a current limiting supply. 🙂