We saw this TLV320 4-channel microphone ADC in an Echo Dot teardown and thought it looked like a handy I2S chip. You can have 4 PDM or analog microphones for input, data comes out on a single stereo I2S channel, with time division multiplexing. Four inputs is better than 2 when using microphones for voice array/location projects. We like that this chip doesn’t need MCLK so it would probably work better with a Raspberry Pi! The chip comes in a few flavors, with 106, 120 or 122 dB SNR (you pay more for the 122!) TLV320ADC5140 (as used in the Echo Dot) is in stock at Digi-Key and We’ll probably use that one. // Read more: original article.