CM108AH Datasheet, PDF (15/27 Pages) C-Media Electronics – Highly Integrated USB Audio I/O Controller

CM108AH
Highly Integrated USB Audio I/O Controller
7.2 Jumper Pins and Mode Setting:
The CM108AH can be configured via several jumper pins. These jumper pin settings affect both USB descriptors
and USB audio topology.
7.2.1 MODE Pin and MSEL Pin
If the MODE pin is pushed up to 3.3V (speaker mode), a playback-only function is activated and no recording
function is declared to the host. At this setting, t h e MSEL pin is ignored and only one input terminal, one
output terminal and one feature unit is declared in the USB audio topology.
If the MODE pin is pulled low (headset mode), a full-duplex playback and recording function is reported to the
host. The MSEL pin setting activates one mixer unit and one feature unit.
 When MSEL = 1, the mixer is enabled (AA-path enabled), but with default mute setting
 When MSEL = 0, the mixer is disabled (AA-path disabled)
The above USB audio topology (7.1.4) is an example of headset mode with enabled mixer.
7.2.2 MODE Pin and PWRSEL Pin
The PWRSEL pin affects the power configuration of the CM108AH. Together with the MODE pin, there are a
total of 4 programmable combinations.
Combinations
PWRSEL
3.3V
GND
MODE
3.3V
GND
Speaker mode:
Headset mode:
Playback only
Playback and recording
(100mA self-powered)
(100mA Bus-powered)
Speaker mode:
Headset mode:
Playback only
Playback and recording
(500mA Bus-powered)
(500mA Bus-powered)
USB Audio Topology Diagram
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Rev. 2.1︱ Page 15/27