# Adafruit MAX98357 I2S Class-D Mono Amp
## Overview
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) is 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 small mono amplifier is surprisingly powerful - able to deliver 3.2 Watts of power 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. Since the amp is a class D, it's incredibly efficient - 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.
The audio input is I2S standard, you can use 3.3V or 5V logic data. 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.
There's a Gain pin that can be manipulated to change the gain. By default, the amp will give you **9dB** of gain. By connecting a pullup or pull down resistor, or wiring directly, the Gain pin can be set up to give 3dB, 6dB, 9dB, 12dB or 15dB.
the ShutDown/Mode pin can be used to put the chip in shutdown or set up which I2S audio channel is piped to the speaker. By default, the amp will output (L+R)/2 stereo mix into mono out. By adding a resistor, you can change it to be just left or just right output
Works great with Raspberry Pi, Arduino Zero, and any other microcontroller or microcomputer with I2S audio outputs
Specs:
- 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
Comes as an assembled and tested breakout board, with a small piece of optional header and 3.5mm terminal block. Some soldering is required to attach the header and terminal block if those are desired.
- [Next Page](https://learn.adafruit.com/adafruit-max98357-i2s-class-d-mono-amp/pinouts.md)
## Primary Products
### Adafruit I2S 3W Class D Amplifier Breakout - MAX98357A
[Adafruit I2S 3W Class D Amplifier Breakout - MAX98357A](https://www.adafruit.com/product/3006)
Listen to this good news - we now have an all in one digital audio amp breakout board that works incredibly well with the [Raspberry Pi](https://www.adafruit.com/category/105)! If you're looking for an easy and low cost way to get your digital sound files...
In Stock
[Buy Now](https://www.adafruit.com/product/3006)
[Related Guides to the Product](https://learn.adafruit.com/products/3006/guides)
## Featured Products
### Speaker - 3" Diameter - 8 Ohm 1 Watt
[Speaker - 3" Diameter - 8 Ohm 1 Watt](https://www.adafruit.com/product/1313)
Listen up! This 3" diameter speaker cone is the perfect addition to any audio project where you need an 8 ohm impedance and 1W or less of power. We particularly like this cone as it has 4 handy mounting tabs 60mm apart.
Works great with our
In Stock
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[Related Guides to the Product](https://learn.adafruit.com/products/1313/guides)
### Speaker - 3" Diameter - 4 Ohm 3 Watt
[Speaker - 3" Diameter - 4 Ohm 3 Watt](https://www.adafruit.com/product/1314)
Listen up! This 3" diameter speaker cone is the perfect addition to any audio project where you need an 4 ohm impedance and 3W or less of power. We particularly like this cone as it has 4 handy mounting tabs 60mm apart.
Works great with our
Out of Stock
[Buy Now](https://www.adafruit.com/product/1314)
[Related Guides to the Product](https://learn.adafruit.com/products/1314/guides)
### Stereo Enclosed Speaker Set - 3W 4 Ohm
[Stereo Enclosed Speaker Set - 3W 4 Ohm](https://www.adafruit.com/product/1669)
Listen up! This set of two 2.8" x 1.2" speakers are the perfect addition to any audio project where you need 4 ohm impedance and 3W or less of power. We particularly like these speakers as they are small and enclosed for good audio volume and quality. The pair have a handy SPK input...
In Stock
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[Related Guides to the Product](https://learn.adafruit.com/products/1669/guides)
### Mini Metal Speaker w/ Wires - 8 ohm 0.5W
[Mini Metal Speaker w/ Wires - 8 ohm 0.5W](https://www.adafruit.com/product/1890)
Listen up! This tiny 1" diameter speaker cone is the perfect addition to any small audio project where you need an 8 Ω impedance and will be using 0.5W or less of power. We particularly like this cone as it's very simple and its metal body is extremely lightweight.
Out of Stock
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[Related Guides to the Product](https://learn.adafruit.com/products/1890/guides)
### Thin Plastic Speaker w/Wires - 8 ohm 0.25W
[Thin Plastic Speaker w/Wires - 8 ohm 0.25W](https://www.adafruit.com/product/1891)
Listen up! This 1.5" diameter speaker cone is the perfect addition to any audio project where you need an 8Ω impedance and are using 0.25W of power. The speakers are rated at 0.25W, with a maximum input of 0.5W (printed wattage on back of speaker may have either value).
We...
In Stock
[Buy Now](https://www.adafruit.com/product/1891)
[Related Guides to the Product](https://learn.adafruit.com/products/1891/guides)
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