Overview

Author Gravatar Image LADY ADA
This incredibly small stereo amplifier is surprisingly powerful - able to deliver 2 x 2.8W channels into 4 ohm impedance speakers (@ 10% THD). 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 it got hot. This board is a welcome upgrade to basic "LM386" amps!

Specifications

  • Output Power: 2.8W at 4Ω, 10% THD, 1.7W at 8Ω, 10% THD, with 5V Supply
  • PSRR: 70 dB typ @ 217 Hz with 6 dB gain
  • Designed for use without an output filter, when wires are kept at under 2"-4" long
  • Four pin-selectable gains: 6dB, 12dB, 18dB and 24dB. Select with the onboard switches or by setting the G0 and G1 breakout pins (see schematic for breakout board showing gain pin settings for details)
  • Excellent click-and-pop suppression
  • Thermal shutdown protection
  • Independent channel shutdown
  • Low current draw: 5mA quiescent and 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 2014-02-04 at 10.44.21 PM