A mini class D with AGC and I2C control? Yes please! This incredibly small stereo amplifier is surprisingly powerful. It can deliver 2 x 2.8W channels into 4-ohm impedance speakers (@ 10% THD) and it has an i2c control interface as well as an AGC (automatic gain control) system to keep your audio from clipping or distorting.
If you don't want to use I2C to control it, it does start up with 6dB gain by default and the AGC is set up for most music playing. We do suggest using it with a microcontroller to configure it, however, since it's quite powerful. Settings are not stored in the chip, so you'll need to adjust any gain & AGC amplification settings every time the amp is powered up.
Inside the miniature chip is a class D controller, able to run from 2.7V-5.5VDC. Since the amp is a class D, it's incredibly efficient (89% efficient when driving an 8Ω speaker at 1.5 watts) - making it perfect for portable and battery-powered projects. It has built-in thermal and over-current protection but we could barely tell if it got hot. This board is a welcome upgrade to basic "LM386" amps!
The inputs of the amplifier go through 1.0uF capacitors, so they are fully 'differential' - if you don't have differential outputs, simply tie the R- and L- to the ground. The outputs are "Bridge Tied" - which means they connect directly to the outputs, with no connection to the ground. The output is a ~300KHz square wave PWM that is then 'averaged out' by the speaker coil - the high frequencies are not heard. All the above means that you can't connect the output to another amplifier, it should drive the speakers directly.
Comes with a fully assembled and tested breakout board with 1.0uF input capacitors. We also include 3.5mm screw-terminal blocks so you can easily attach/detach your speakers, and some header in case you want to plug it into a breadboard. Speakers are not included, use any 4-ohm or 8-ohm impedance speakers.
Our awesome tutorial and Arduino library will let you set the AGC configuration (you can also just turn it off), max gain, and turn on/off the left & right channels all over I2C! You will be ready to rock in 20 minutes!
Note: The terminal blocks included with your product may be blue or black.
Speakers, cables, breadboard and Arduino board are NOT included
Revision History
As of August 19th, 2024 – we've updated this PCB with Adafruit Pinguin to make a lovely and legible silkscreen - you may get the new PCB or the older version with vector fonts - both are identical other than the fancy silkscreen.
Specifications
Output Power: 2.8W at 4Ω, 10% THD, 1.7W at 8Ω, 10% THD, with 5V Supply
PSRR: 80 dB, 5ms startup time
Designed for use without an output filter, when wires are kept at under 2"-4" long
I2C interface pins for setting gain, AGC configuration parameters, etc. See our tutorial for more details
Selectable gain from -28dB to 30dB
Excellent click-and-pop suppression
Thermal shutdown protection
Shutdown pin for power saving mode.
Low current draw: 3.5mA quiescent and 0.2uA in shutdown mode
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