CM108AH Datasheet, PDF (1/27 Pages) C-Media Electronics – Highly Integrated USB Audio I/O Controller

CM108AH
Highly Integrated USB Audio I/O Controller
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
BLOCK DIAGRAM
REGV
PWRSEL
MODE
PDSW SEL pins
VOLUP
VOLDN
MUTER LEDO MCU
MUTEP LEDR I/F GPIO BUZZ SPDIFO
CS
SK
DW
DR
USBDP
USBDM
XI
XO _{12 MHz}
5- > 3. 3
regulator
USB interrupt
processing with4
byte FIFO
3.3V
EEPROM
interface
USB
TRX
USB
interface
4 byte
FIFO
USB control
processing
ISO out
processing
( with x2 mod)
12. 288/11. 2896 MHz
with adjustment
48 MHz
PLL1
PLL2
ISO in
processing
interface logics
ROM
300 x 16 SRAM
High-Pass Filter
PLL3 _12.288/
11. 2896MHz
IIS I/F
VREF
(2.25V)
bandgap
TEST
reset power on
reset
16 bit
DAC
sync by
VPR_ CLK
0 ~-45dB
38 steps
voltage linear
+
Vref
+
Vref
+
Vref
16 bit
DAC
16 bit Sigma-
Delta ADC
Vref ⁺
0 ~-45dB
38 steps
sync by voltage linear
VPL_ CLK
+ _Vref
+
Vref
+22.5~ - 0 dB
16 steps
+ Vref
BOOST
+22.5 dB boost enable
4.5 V( drive typ4mA)
+22. 5 ~ 0 dB
16 steps
LOR
LOBS
LOL
MICIN
VREF
VBIAS
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Rev. 2.1︱ Page 1/27