Overview

Author Gravatar Image LADY ADA
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!

Our 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!

adafruit_products_1712front_LRG.jpg

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 the Software page 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

What is a Class D Amplifier?


A Class D Amplifier uses PWM to generate high-frequency square waves with a duty-cycle proportional to the voltage level of the input audio signal. By minimizing the transition time between fully on and fully off, the MOSFET drivers are able to operate at a very high efficiency. Class D amplifiers such as this one typically operate at over 90% efficiency, compared to efficiencies of 50% or less for typical class AB amplifiers.

The high frequency square-wave component of the output signal is filtered by the inductance of the speaker voice coil, leaving only the amplified audio signal.

Other Audio amps available at Adafruit


We have a few choices of audio amplifiers, here's how you can compare them

  • MAX98306 - This class D audio amplifier has selectable gains of 6dB, 9dB, 12dB, 15dB and 18dB that you can choose with a jumper. It can do up to 3.7W into 3Ω, 2.8W into 4Ω and 1.7W into 8Ω. However, you cannot shut down each speaker separately. Its a good choice where you don't mind setting the gain with a jumper and if you do not need to ever turn off only one audio channel and you do not need more than 18dB. Its an excellent amplifier that can driver down to 3Ω speakers
    Like the TS2012, it has differential inputs, bridge tied outputs, and can run from 2.7V to 5.5V

  • TS2012 - This class D audio amplifier has selectable gains of 6dB, 12dB, 18dB and 24dB that you can choose with a jumper (the MAX98306 goes up to 18dB only). It can do up to 2.8W into 4Ω and 1.7W into 8Ω. It cannot drive 3Ω. You can shut down each channel separately. Setting the gain is easy on the onboard DIP switches. Its a good choice where you don't need to drive 3Ω speakers or if you ever want to turn off only one audio channel. If you need 24dB gain this amp can do it.
    Like the MAX98306, it has differential inputs, bridge tied outputs, and can run from 2.7V to 5.5V
Last updated on 2014-04-24 at 03.41.15 PM Published on 2014-02-07 at 10.30.26 PM