C371346_375F2440A66FD1C882296D07948AE54C.pdf
CM 108AH Highly Integrated USB Audio I/O Controller www .cmedia.com.tw Copyright© C-Media Electro nics Inc. R ev . 2.1 ︱ P age 1 /27 USB TRX USB interface 4 byte FIFO USB control processing ISO out processing ( with x2 m…
CM108AH
Highly Integrated USB Audio I/O Controller
www.cmedia.com.tw
Copyright© C-Media Electronics Inc. Rev. 2.1︱ Page 1/27
USB
TRX
USB
interface
4 byte
FIFO
USB control
processing
ISO out
processing
( with x2 mod)
PLL1
48 MHz
ROM
PLL2
12. 288 /11. 2896 MHz
with adjustment
12 MHz
VREF
(2.25V)
power on
reset
reset
16 bit
DAC
bandgap
3.3V
+
-
+
-
Vref
5 - > 3. 3
regulator
REGV
ISO in
processing
300 x 16 SRAM
16 bit Sigma-
Delta ADC
16 bit
DAC
+
-
Vref
+22.5~ - 0 dB
16 steps
Vref
PLL3
12.288/
11. 2896 MHz
USB interrupt
processing with 4
byte FIFO
interface logics
MUTER
MCU
I/F
VOLDN
VOLUP
VREF
MUTEP
LOL
LOR
LEDO
LEDR
PDSW
+
-
+22. 5 ~ 0 dB
16 steps
Vref
0 ~ -45dB
38 steps
voltage linear
VBIAS
4.5 V ( drive typ 4mA)
EEPROM
interface
CS
SK
DW
DR
USBDP
USBDM
XI
XO
MICIN
+
-
Vref
Vref
+
-
+
-
Vref
LOBS
GPIO
BOOST
+22.5
dB boost enable
0 ~ -45dB
38 steps
voltage linear
PWRSEL
MODE
SEL pins
TEST
sync by
VPR_CLK
sync by
VPL_CLK
BUZZ
IIS I/F
SPDIFO
High-Pass Filter
BLOCK DIAGRAM
DESCRIPTION
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.
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
CM108AH
Highly Integrated USB Audio I/O Controller
www.cmedia.com.tw
Copyright© C-Media Electronics Inc. Rev. 2.1︱ Page 2/27
TABLE OF CONTENTS
1 Description and Overview .............................................................................................. 3
2 Features ................................................................................................................... 3
3 Pin Descriptions .......................................................................................................... 5
3.1 Pin Assignment by Pin Number ............................................................................... 5
3.2 Pin-Out Diagram ................................................................................................ 5
3.3 Pin Signal Descriptions ........................................................................................ 6
4 I²S Interface .............................................................................................................. 8
5 Block Diagram ............................................................................................................ 9
6 Ordering Information ................................................................................................... 10
7 Function Description ................................................................................................... 11
7.1 USB Interface .................................................................................................. 11
7.1.1 Device Descriptor ................................................................................... 11
7.1.2 Configuration Descriptor .......................................................................... 12
7.1.3 Content Format for EEPROM (93C46) ............................................................ 13
7.1.4 USB Audio Topology Diagram ..................................................................... 14
7.2 Jumper Pins and Mode Setting: ............................................................................. 15
7.3 HID Feature .................................................................................................... 16
7.3.1 What’s HID? .......................................................................................... 16
7.3.2 HID Descriptor ....................................................................................... 17
7.3.3 Windows Software Architecture for HID ........................................................ 18
7.4 Internal Registers ............................................................................................. 19
8 Electrical Characteristics .............................................................................................. 22
8.1 Absolute Maximum Rating ................................................................................... 22
8.2 Operation Conditions ......................................................................................... 22
8.3 Electrical Parameters ........................................................................................ 23
9 Audio Quality Graphs ................................................................................................... 24
9.1 Line Out Frequency Response @ 48KHz Sample Rate (10K Ohm Loading) .......................... 24
9.2 Line Out THD+N @ 48KHz Sample Rate (10K Ohm Loading) ........................................... 24
9.3 Microphone Input Freq Response @ 48KHz Sample Rate ............................................... 25
9.4 Microphone Input THD+N @ 48KHz Sample Rate ........................................................ 25
Reference ....................................................................................................................... 26
CM108AH
Highly Integrated USB Audio I/O Controller
www.cmedia.com.tw
Copyright© C-Media Electronics Inc. Rev. 2.1︱ Page 3/27
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