The TPA2028D1 is a Class D power amplifier integrated circuit (IC), manufactured by the Texas Instruments Corporation. It provides 3 W output into a 4 Ω speaker when the power supply is 5 V, or 880 mW into an 8 Ω speaker with a 3.6 V supply. It has a very small footprint of 1.63 mm × 1.63 mm and arrives in a wafer chip-scale package (WCSP).
This IC has an intelligent DRC / AGC control circuitry that compresses the dynamic range of sound to fit within the dynamic range of the speaker. This has the amazing result of eliminating distortion, as well as enhancing the quieter parts of the audio. It can produce a “big” speaker sound, from a small speaker, which is very interesting.
This chip also has a digital volume control facility through the I²C bus, thus eliminating the need to use rotary potentiometers.
Class D Tape Recorder
Class D operation is extremely efficient and the power consumption of this IC is remarkably small. Just as an experiment, I replaced the electronic circuitry of a vintage cassette recorder to see how this modern technology would sound and it produced exceptionally high quality audio.
The only downside with this IC is that they do not produce it in a DIP package, which would be extremely useful for students and hobbyists. However, I am sure a Chinese firm will produce a PCB adapter, which converts the package to DIP, or at least something easier to handle.