Bluetooth Headphone Amplifier

The headphone amp chip uses TPA6120A2RGYR dual power supply, and the chip
data link that can leave tears of regret even if the wires are randomly flown is
https://www.ti.com.cn/cn/lit/ds/symlink/tpa6120a2.pdf?ts=1652340071483&ref_url=https%253A%252F%252Fwww.ti.com.cn%252Fproduct%252Fzh-cn%252FTPA6120A2
I used the reference design on page 14.
A self-locking circuit was added to control the enable of DCDC (DCDC is more power-consuming).
The power button actually controls the self-locking circuit to keep the chip enable pin of DCDC at a high level
. Just turn off and press it again. When the power is turned off (standby is more accurate), only the Bluetooth module consumes power, remember it is 3mA.
I added an SL3105A to charge the lithium battery.
The Bluetooth audio module uses differential analog audio output. The chip is Qualcomm QCC3034, which supports APTX_HD. The
audio module only uses audio output and key functions.
The PCB doesn't matter. The differential analog signal (the line is very short and the frequency is very low, so there is no need to deliberately differential routing) is still very friendly. Just share a ground.
The GND should be as complete as possible. At most, you can make a few more vias.
The power supply uses solder points, and you can put any lithium battery (a string). I use 18650. Theoretically, the standby time is hundreds of hours, but I haven't tried it every day.