Easy-to-solder QCC5125 + PCM5102 Bluetooth decoding headphone amplifier

Version
1.0 fixed the error of reversed diodes in the power management module schematic. Power module verification completed.
1.1 Fixed some minor bugs. Testing completed, can be used normally.
1.2 Fixed some major bugs. Used a ready-made power management module from Taobao. Testing completed. This is the final version of this project.
Note:
It is not recommended to use solder paste to solder the Bluetooth module, as it is easy to cause solder bridging (
pay attention to solder bridging at the C port). Before powering on, measure whether each power supply is short-circuited to ground
. The opening for the capacitor in the current version seems to be too small. It is recommended to enlarge the hole yourself with a file.
The manufacturer's specifications are in the attachment.
It cannot charge after the switch is turned off. These minor issues will be addressed in a new project later (just kidding).
Design goal:
Supports LDAC encoding HIFI (realistic) Bluetooth decoder, small size of 23*70mm (as you can see, it can be compressed), low soldering difficulty, complete button control
architecture.
Uses QCC5125 ready-made Bluetooth module IIC output, Bluetooth up to LDAC. 96kHz 24bit, USB input 48kHz 16bit (this is a bit of a drawback). After decoding with PCM5102, the output is amplified by LM4881.
The power supply design uses a battery, boosted to 6V by MT3608DCDC, and then regulated by three ME6211LDOs to provide two 3V/3V and 5V channels to power the Bluetooth module, decoder, and headphone amplifier respectively. TP4057 manages charging.
The current version uses a Taobao integrated charging/discharging module.
Note that
I am a complete novice, heavily referencing other engineering designs, and the schematics are patched up. The main design has been verified.
There is limited information on the MT3608; the design referenced is a module from Taobao, and its practicality needs further verification.
Cost calculation:
46 RMB, AL5125 module
5 RMB, Youxin Electronics PCM5102A. The total cost is approximately 80 yuan, including
3 yuan for the LM4881 and 20 yuan
for other components. Further improvements are suggested, such as replacing the DAC with a newer one and a better headphone amplifier (e.g., ES9018 + MAX97220). The THD+N parameters of the LM4881 are indeed not ideal. According to the datasheet, at 32 ohms impedance and 75mW output power, the THD+N is 0.02%, which is not very impressive. Improve charging management by adding independent charging and DC-DC output sections to avoid the current inconvenience of having to keep the device powered on to charge. Modularize the Bluetooth section by adding a separate USB interface to create a modular Bluetooth and USB integrated dock (or even a high-end independent power supply). See the project/ramblings here : https://oshwhub.com/w565670605/qcc3034-lan-ya-5-2-er-fang-_2024-03-24_16-15-24 This project (https://oshwhub.com/xyzdiy/hifi-lan-ya-yin-xiang ) extensively uses 0603 packages to facilitate soldering for someone like me with clumsy hands. A separate small board is used for power management to reduce layout complexity, and an external antenna further simplifies the design. The QCC5125 and QCC3034 module pins should be compatible; refer to the manufacturer's manual for details. The rules for copper plating and forbidden areas in the power module haven't been changed, so there might be minor issues when opening it. You can try modifying it yourself . This is a beginner's attempt; anything missing will be modified later.