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.
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.
- 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