CM108B Datasheet, PDF (10/24 Pages) C-Media Electronics – A Highly Integrated USB Audio Single Chip

CM108B
USB Audio Single Chip
6 I2S Interface
The CM108B provides an I2S interface for both playback and recording. External ADC, DAC, or DSP can be added to
provide additional functions within the USB audio system. The CM108B sends out master clock (fixed at x256), LRCK
(fixed at x64), and data clock data. Therefore, external ADCs, DACs, or DSPs should be set to slave mode.
The left channel of the CM108B’s I2S bus is used for mono recording. Both IP^2PS buses use a 5V tolerant pad in order
to easily interface with 5V or 3.3V devices. Playback data is simultaneously sent to both the DAC and I2S bus. The
recording source (ADC or I2S bus) can be selected by ADSEL jumper pin.
LRCK
SCLK
SDATA
Left Channel
MSB -1
-2
+2 +1 LSB
Right Channel
MSB -1
-2
+2 +1 LSB
Datasheet Revision: 1.11
Page 10 / 24
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