This small breakout board combines Bluetooth 5.0 reception with a digital 2x5W stereo amplifier. It is based on the 5W PAM8406 digital power amplifier module.
There are many variations of this board available with subtle differences in board design and functionality. Some even ship with separate external remote control.
Where To Use
This board comes with everything needed to built a small bluetooth-ready sound box. The output volume is moderate but sufficient (2x5W).
Technical Data
| Item | Description |
|---|---|
| Power Supply | Micro USB, one lithium cell, external 3.7-5V supply |
| Audio Amplifier | 2x5W @ 2Ohm Speakers |
| Speakers | 2x 2-8Ohm |
| Speaker Impedance | 2-8 Ohm (5W@2Ohm, 3W@4Ohm, 2W@8Ohm) |
| Audio In | Headphone Jack 3.5mm |
| Audio Frequency | 20-20kHz |
| Bluetooth Distance | <15 Meter, SNR >= 90dB |
| Size | 43x33x5mm |
Power Supply
The board can be supplied with power in many ways due to its wide voltage range:
- Micro-USB: connect a common smartphone charger via USB (2A or better)
- Lithium battery: power the board with one common LiIon or LiPo cell (4A)
- External: connect to car voltage or any other power supply (3.7-5V)
Insufficient power supplies negatively affect sound quality.
Using Lithium Battery
The board power can be supplied by a single LiIon or LiPo battery. The board automatically turns off when the input voltage drops below 3.3V, protecting lithium batteries from over-discharge.
Once over-discharge protection has kicked in and automatically turned off the board, after recharging the battery power on the board again. To unlock the protection, it may be necessary to connect the on pins for at least 2 seconds (if you connected an on/off push button to this port, press the button for >2sec.)
When you power this board via battery, and the battery is approaching its empty state, the voltage falls to a level where the board starts making “sizzling” noises. This can be used as an indicator to recharge batteries before over-discharge protection kicks in.
The lithium battery can be directly charged via the Micro USB connection.
Never operate lithium batteries without battery protection board (BMS): check your battery to find out whether it has a built-in BMS.
Audio Out
Audio can be played to headphones via 3.5mm headphone jack, or by connecting two speakers with common ground to the speaker pins.
Volume is controlled by a half-rounded switch:
- Volume: turn switch towards the USB connector to lower volume, and turn it to the other direction to raise it.
- Play/Pause: press the button to toggle play and pause.
Behind the volume control switch, the breakout board comes with two solder pads. Connecting these pads for >2s toggles between on and off.
Bluetooth Connect
After supplying power, a blue LED starts blinking. The device is now in bluetooth pairing mode and can be detected by i.e. your smartphone.
Once a bluetooth connection is made and the board is coupled, the blue LED stops blinking and lights constantly.
When music is played back, the blue LED flashes slowly.
All Bluetooth functionality is provided by a AC… chip manufactured by Zuhai Jie Li. This company produces cheap chips for a wide variety of consumer products.
Data Sheet
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(content created Apr 04, 2024 - last updated Apr 13, 2024)