CM108 Datasheet, PDF (11/29 Pages) C-Media Electronics – USB Audio I/O Controller

CM108
Integration Dual DAC, Earphone Driver, ADC,
Microphone Booster, PLL, Regulator, and USB Transceiver
4. I²S INTERFACE
CM108 provide I²S interface for both playback and recording. External ADC, DAC, or DSP
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can be added to provide additional function in the USB audio system. CM108 sends out the
master clock (fixed at x256), LRCK (fixed at x64), and data clock. Therefore external ADC,
DAC, or DSP should be set at slave mode for I²S interface. Left channel of I²S bus is used for
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CM108 mono recording. Both I²S buses use 5V tolerant pad so they can be easily interfacing
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with 5V or 3.3V devices. Playback data is simultaneously sent to both DAC and I²S bus.
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Recording source (from ADC or from I²S bus) can be selected by ADSEL jumper pin.
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LRCK
SCLK
SDATA
Left Channel
MSB -1 -2
+2 +1 LSB
Right Channel
MSB -1 -2
+2 +1 LSB
Date: Nov/01/2004
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Version: 1.5