[Hi-Res] Class D digital amplifier based on TAS5825M

Disclaimer:
Although it is an open source project, there are some problems in the design, and it is basically impossible to reproduce, so the source code/firmware is not provided. You can just watch it for fun and envy.
 
Features:
Flexible audio input:
   -Support USB2.0 high-speed audio input, support 32kHz, 44.1kHz, 48kHz, 88.2kHz, 96kHz and 192kHz sampling rates and 16bit, 24bit, 32bit bit width
   -Support Bluetooth LDAC, Aptx and other inputs, up to 96kHz sampling rate, 24bit bit width
High-efficiency Class D power amplifier:
   -Low power requirement for power supply, basically no heat
High output power:
   -Support 2x30W dual-channel output, the minimum load is 4Ω
Flexible power configuration:
   -DC005 interface input, 4.5~24V
 
Description:
TAS5825M is a 38W stereo, 65W mono, 4.5V to 26V, digital input Class D smart audio amplifier with 192kHz architecture. With Amanero digital interface and QCC5125 module, it can realize high-definition USB and Bluetooth LDAC audio input, thus meeting desktop HiFi needs.
 
 
System architecture:
The amplifier is composed of five parts: 1. TAS5825M digital audio amplifier; 2. STM32F051 controller; 3. QCC5125 Bluetooth audio module; 4. Amanero digital interface; 5. USB PD power supply module (not used). The circuit uses a two-layer PCB (the four-layer PCB was still 5cmx5cm free at the time, and the professional version was not easy to use).
 
 
1. TAS5825M digital audio amplifier
        uses Texas Instruments' TAS5825M digital amplifier chip as the main amplifier. The chip uses I2S digital output and has a switching frequency of up to 768kHz, which can simplify filter design and retain high-frequency audio signals to meet the basic requirements of Hi-Res. Because the chip integrates digital-to-analog conversion and Class D amplifier, there is no need for additional decoding chips and amplifier chips, achieving true monolithic integration, greatly reducing PCB area and simplifying circuit design.
        TAS5825M needs to be configured using I2C and cannot run alone. It supports multiple ways of playing, such as changing the volume. There is no POP sound when it is powered on, and there is no background noise when it is silent. There are no problems in other analog Class D amplifiers.
        This amplifier configures TAS5825M as BTL output, and has two independent amplifiers, that is, 4-way output, designed to separate treble and bass (later it was found that there would be a large background noise when two amplifiers worked at the same time, so the other channel was not used)
2. The STM32F051 controller
        MCU is responsible for the power on and off of the amplifier, the USB/Bluetooth switching of the audio signal, the configuration of the amplifier and the volume adjustment, and is equipped with an automatic shutdown function. When there is no audio signal input for a long time, the amplifier is automatically shut down to reduce power consumption.
3. QCC5125 Bluetooth audio module
        The Bluetooth module is responsible for receiving Bluetooth audio signals. The version that supports LDAC is used to meet the requirements of high-definition audio.
4. Amanero digital interface
        The digital interface is responsible for USB audio stream input.
        The switching between USB audio stream and Bluetooth audio stream is controlled by MCU SN74LVC244 for switching.
5. USB PD power supply module (unused)
        is designed with Type C PD power supply, but there is no PD charger, so I simply didn't solder it. The chip was not easy to buy at that time. I used the CH244K PD deception chip, which supports PD 20V input at most.
 
User experience:
        It is used with a 4-inch full-range speaker, which basically reaches the level of HiFi products on the market. Because it uses USB input, you don't have to worry about the problem of high noise when the volume is turned up, and you don't have to worry about other interference. Even if you don't turn it off at night, it will turn off automatically. If you don't turn on the computer occasionally, you can turn on Bluetooth to connect your phone to play music.
        The two-layer board is not very good, but now the four-layer can't use mixed colors (sad).
        Only one of the two-way amplifier is used, which is a bit wasteful.
        There is no shell, so it is easy to accumulate dust. But I can't make a shell myself. If there is an expert who makes a shell, you can cooperate with me to make a new model.
Material source/price:
This item determines whether you can reproduce
the TAS5825M chip. At that time, it was about 50 pieces, but now it is out of stock, and it is not easy to buy even if you have money.
STM32F051 chip, at that time, it was 4 yuan per piece, and now it costs 16+.
Amanero digital interface, at that time, 140 yuan per piece, now slightly reduced.
QCC5125 Bluetooth module LDAC model, now 48 yuan per piece
, power amplifier, inductor and capacitor, about 10 yuan per channel.
 
Picture: