Class D amplifier TPA3126D2 chassis version. A high-quality desktop mini amplifier for your study! Utilizing the Class D amplifier TPA3126D2 chassis version, we will integrate Bluetooth and aux inputs, along with a built-in switch power supply. Let’s work together to achieve great sound quality and eliminate pop noise. Check out TI’s document on reducing pop noise in class D amplifiers for further research. Let’s make some music!

Background Found a pretty good-looking amplifier shell on Taobao, and happened to have a small amplifier in the study. So I decided to make a desktop mini amplifier for the study.

The design goal is to integrate Bluetooth and aux inputs, and have a built-in switch power supply. The sound quality should be decent.

Design solution Power: Selected a 24V 5A LCC power module.

The circuit design is relatively simple:

1. The amplifier chip chosen is TPA3126D2. Without considering THD+N, it can achieve 2×50W output power when driving a 4 Ω load. In actual use with sensitive bookshelf speakers, the output power is usually small, basically not exceeding 10Wx2.
2. The operational amplifier used is TL072.
3. The Bluetooth module selected is the Qualcomm QCC3034 module (I2S output, mainly because I happened to have one).
4. The Bluetooth module DAC is ES9023. Since it is just an amplifier for casual listening, there is no specific high requirement on sound quality. A relay switches to the Bluetooth input when connected, and to avoid trouble, a transformer coupling is added to the Bluetooth audio.

Schematic Class D amplifier TPA3126D2 chassis version

The amplifier output low-pass filter uses a large power common mode inductor specifically designed for digital amplifier audio. The sound quality is decent when actually listening. About eliminating pop noise, TI has a document discussing how to eliminate pop noise in their class D amplifier chips. You can go check it out for further research.

The fundamental reason for pop noise is mismatched input signals, such as mismatched positive and negative impedance, etc.

The main ways to reduce pop noise are:

1. Reduce input capacitance;
2.  Lower the gain;
3. Control output on/off;
4. Control the timing of chip power up and down.

In this design solution:

1. The input coupling capacitor uses a 3.3uf ceramic capacitor
2.  A reset chip is used to control the mute during power-up and down processes. It opens with a delay during power up and shuts off instantly when power is cut.

BOM Class D amplifier TPA3126 chassis version

Download files, links, and notes

• Download PCB in Gerber + BOM + Centroid File
• Mirror
• PDF Datasheet tpa3126d2
• PDF Datasheet IC ES9023
• PDF Datasheet IC MP2359
• PDF Datasheet IC ME6231
• PDF Datasheet IC NE5532
• PDF Datasheet QC3034
• Buy 24V 5A LCC power module
• Buy QCC3034 module
• Buy Aluminum Power Amplifier Chassis Enclosure
• Buy IC ES9023
• Buy IC TPA3126D2
• Buy TPA3126D2 Bluetooth 5.0 QCC3034 Module

source: https://oshwhub.com/qsszbsc/class-d-amplifier-tpa3116d2-chassis-edition