A mini class D with AGC and I2C control? Yes please! This incredibly small stereo amplifier is surprisingly powerful. It is able to deliver 2 x 2.8W channels into 4 ohm impedance speakers (@ 10% THD) and it has a 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 on with 6dB gain by default and the AGC set up for most music playing. We do suggest using it with a microcontroller to configure it, however, since its 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 Watt) - 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 ground. The outputs are "Bridge Tied" - that means they connect directly to the outputs, no connection to 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 into 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.
Technical Details
Revision History:
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As of November 2022 – 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.
Specs:
- 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
