I2S Digital Audio Amplifier Class D Module - MAX98357

If your microcontroller or microcomputer has digital audio capability, this amp is for you! It takes standard I2S digital audio input and, not only decodes it into analog, but also amplifies it directly into a speaker. Perfect for adding compact amplified sound, it takes 2 breakouts (I2S DAC + Amp) and combines them into one.

I2S (not to be confused with I2C) in a digital sound protocol that is used on circuit boards to pass audio data around. Many high end chips and processors manage all of the audio in digital I2S format. Then, to input or output data, three or four pins are used (data in, data out, bit clock and left-right channel select). Usually, for audio devices, there's a DAC chip that will take I2S in and convert it to analog that can drive a headphone.

This board will save you time and is both 3.3V and 5V tolerant. The amplifier offers 3.2 Watts into a 4 ohm impedance speaker (5V power @ 10% THD). Inside the miniature chip is a class D controller, able to run from 2.7V-5.5VDC. 

The outputs are "Bridge Tied" - that means they connect directly to the speaker terminals. The output is a ~300KHz square wave PWM that is then 'averaged out' by the speaker coil - the high frequencies are not heard. Do not connect to another amplifier's input.

You can adjust the again using the pins, default is 9dB and can be adusted to give 3dB, 6dB, 9dB, 12dB or 15dB.

Specifications

• Output Power: 3.2W at 4Ω, 10% THD, 1.8W at 8Ω, 10% THD, with 5V supply
• PSRR: 77 dB typ @ 1KHz 
• I2S sample rates from 8kHz to 96kHz
• No MCLK required
• Click + Pop reduction
• Five pin-selectable gains: 3dB, 6dB, 9dB, 12dB, 15dB
• Excellent click-and-pop suppression
• Thermal shutdown protection

More information

• Download MAX98357 datasheet (pdf)
• adafruit-max98357-i2s-class-d-mono-amp