CM108AH Datasheet, PDF (3/27 Pages) C-Media Electronics – Highly Integrated USB Audio I/O Controller

CM108AH
Highly Integrated USB Audio I/O Controller
1 Description and Overview
The CM108AH is a highly integrated single-chip USB audio solution. All essential analog modules are embedded
in the CM108AH, including dual DAC and earphone driver, ADC, microphone booster, PLL, regulator and USB
transceiver modules. It is perfectly suited to USB headset, USB earphone or USB audio-interface box
applications. As well, many features are programmable with jumper pins or by external EEPROM.
Audio adjustments are easily controlled via specific HID-compliant volume control pins. An external codec or
audio DSP can be connected to the CM108AH via I2S pin for further processing. Plus, 3 GPIO pins can be
accessed with customer application software for additional value-adding applications.
2 Features
 Supports USB 2.0 full speed operation
 Compliant with USB audio device class specification 1.0
 Supports USB suspend/resume modes and remote wakeup with volume control pins
 Single 12MHz crystal input with on-chip PLL and embedded USB transceiver
 Jumper pin for speaker mode (playback only) or headset mode (playback plus recording)
 For headset mode, USB audio function topology has 2 input terminals, 2 output terminals, 1 mixer unit, 1
selector unit and 3 feature units
 Jumper pin allows for mixer unit enable/disable when in headset mode
 For speaker mode, the USB audio topology has 1 input terminal, 1 output terminal and 1 feature unit
 Supports one control endpoint, one isochroous OUT endpoint, one isochroous IN endpoint, and one
interrupt IN endpoint
 Alternate zero bandwidth setting for releasing playback bandwidth on USB Bus when device is inactive
 Supports AES/EBU, IEC60958, S/PDIF consumer formats for stereo PCM data at S/PDIF output
 Volume up, volume down, and playback mute pins support USB HID for host control synchronization
 Record mute pin with LED indicator for record mute status
 External EEPROM interface for vendor-specific USB VID, PID and serial number
 EEPROM write function via vendor-specific request for mass production convenience
 Customized embedded VID, PID, product and manufacturer strings and volume settings are available
 3 GPIO pins with read/write via HID interface
 Jumper pin to set the power mode (100mA or 500mA, Bus-powered or self-powered)
 Isochronous transfer uses adaptive mode with internal PLL for synchronization
 48K/44.1KHz sampling rate for both playback and recording
 Soft mute function
 Embedded high-performance 16-bit audio DAC with earphone phone amplifier
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