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Adafruit I2S 3W Class D Amplifier Breakout - MAX98357A
It takes a standard I2S digital audio input and not only decodes it into analog but also directly amplifies it to drive a speaker. Perfect for adding compact amplified sound, it takes 2 inputs (I2S) and combines them into one output.
I2S is a digital audio protocol used to transmit audio data in digital form between microcontrollers or microprocessors and audio devices, and it should not be confused with I2C. Many high-end chips and processors manage all audio in the digital I2S format. Data input or output typically uses three or four pins (data in, data out, bit clock, and left-right channel select). For most audio devices, there is a DAC (Digital-to-Analog Converter) chip that takes the I2S and converts it into an analog signal that can be used to drive headphones or speakers.
This compact mono amplifier is surprisingly powerful, capable of delivering 3.2 Watts of power to a 4-ohm speaker when powered with 5V at 10% Total Harmonic Distortion (THD). Inside the miniature chip is a Class D controller that operates from 2.7V-5.5VDC. Being a Class D amplifier, it is incredibly efficient, making it perfect for portable and battery-powered projects. It includes built-in thermal and over-current protection, but it's hard to tell if it ever overheats!
The audio input is in the I2S standard, and you can use 3.3V or 5V logic levels. 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's designed to drive speakers directly.
There's a Gain pin that can be manipulated to change the gain. By default, the amplifier will give you 9dB of gain. By adding a pullup or pulldown resistor or by directly wiring it up, the Gain pin can be adjusted to provide 3dB, 6dB, 9dB, 12dB, or 15dB of gain as needed.
The Shutdown/Mode pin can be used to turn off the chip or configure which I2S audio channel is routed to the output. By default, the amplifier outputs a (Left+Right)/2 stereo mix to the mono output. Adding a resistor allows you to switch it to either the left or right output.
It works great with Raspberry Pi, Arduino Zero, and other microcontrollers or microcomputers with I2S audio output.
- Output Power: 3.2W at 4Ω, 1.8W at 8Ω, 10% THD, with 5V supply
- PSRR: 77dB typical @ 1kHz
- I2S sample rates from 8kHz to 96kHz
- No MCLK required
- Click-and-pop reduction
- Five-pin selectable gain: 3dB, 6dB, 9dB, 12dB, 15dB
- Perfect click-and-pop suppression
- Thermal shutdown protection
It comes as a mounted and tested circuit board with a small optional header and a 3.5mm terminal block. If desired, a small amount of soldering is required to attach the header and terminal block.
Note: The terminal block included with your product may be blue or black.
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- MAX98357 Datasheet
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