CM108B Datasheet, PDF (1/24 Pages) C-Media Electronics – A Highly Integrated USB Audio Single Chip

CM108B
USB Audio Single Chip
A Highly Integrated USB Audio Single Chip
DESCRIPTION
The CM108B is a highly integrated crystal-free USB
audio single chip solution optimized for USB
headset, headphone, and dongle applications. The
CM108B comes with software driver interface
which supports Xear^TM sound effects for
multimedia entertainments. All essential analog
modules are embedded in the CM108B, including
dual DAC and earphone driver, ADC, microphone
booster, PLL, regulator and USB transceiver
modules. 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
CM108B via I2S pin for further processing. Vendors
can customize unique USB VID/PID/Product
String/Manufacture String and min/max/initial
volumes to EEPROM. The CM108B also comes with
an anti-pop noise circuits design and internal
oscillator which can operate without an external
crystal oscillator.
FEATURES
 Compliant with USB 2.0 Full Speed Operation
 Compliant with USB Audio Device Class
Specification v1.0
 Supports USB Suspend/Resume Mode and Remote
Wakeup with Volume Control pins
 On-chip oscillator that provides reference sources
for PLL and embedded USB transceiver
 Jumper pin for Headset Mode (Playback +
Recording) and Speaker/Headphone Mode
(Playback Only)
 Jumper pin for Mixer Unit enable/disable under
Headset Mode and Power Mode setting
 I2S interfaces for external CODEC
 Anti-pop noise design for plugged and vice-versa
 Support Xear^TM Audio Centre Software Driver for
Windows OS
BLOCK DIAGRAM
PWRSEL
MODE
AREG36 DREG33 DREG18 ^PDSW MSEL
3.6V 3.3V 1.8V
Regulator
5->3.6, 3.3 & 1.8
DW
DR
SK
SPI
CS
EEPROM
Interface
USBDP
USBDN
USB
USB TRX
USB
Interface
RF
PLL
48M
12M
VOLUP
VOLDN
MUTER
MUTEP
DASCLK/ADSCLK
DALRCK/ADLRCK
LEDO
DAMCLK/ADMCLK
LEDR GPIOs SDOUT/SDIN
Interface Logics
I2S Out/In
USB Control
ISO Out
Processing
16 bit
DAC
16 bit
DAC
VREF
0 ~ -45dB
0 ~ -45dB
ISO In
Processing
SRAM
16 bit
ADC
VREF
8 ~ -22dB
23 ~ -22dB
12dB/22dB
Booster
bandgap
LOBS
LOR
LOL
MICI
N
VREF
(1.75V)
VBIAS
(3V)
Datasheet Revision: 1.11
Page 1 / 24
www.cmedia.com.tw
Copyright© C-Media Electronics Inc.