CM108AH Datasheet, PDF (11/27 Pages) C-Media Electronics – Highly Integrated USB Audio I/O Controller

CM108AH
Highly Integrated USB Audio I/O Controller
7 Function Description
7.1 USB Interface
The CM108AH integrates USB transceiver, PLL and regulator modules, meaning only a few passive components
are necessary for USB interface connection. Default USB descriptors are embedded in the CM108AH, so no
additional design effort is needed for generic USB operation. For custom orders, customers can attach a
93C46 EEPROM to override the embedded VID, PID, product and manufacturer strings, and serial number for
each set. The CM108AH automatically detects the 93C46, and the overwrite function is performed at start up.
7.1.1 Device Descriptors
Offset
0
1
2
4
5
6
7
8
10
12
14
15
16
17
Field
bLength
bDescriptorType
bcdUSB
bDeviceClass
bDeviceSubClass
bDeviceProtocol
bMaxPacketSize0
idVendor
idProduct
bcdDevice
iManufacturer
iProduct
iSerialNumber
bNumConfigurations
Size
1
1
2
1
1
1
1
2
2
2
1
1
1
1
Value (Hex)
Description
12 Total: 18 bytes
01 Device descriptor
0110 USB 1.1-compliant
00
00
00
40 Endpoint zero size = 64 bytes
0d8c Vendor ID
0139 Product ID programmable by MSEL and MODE pin
0100
Device compliant with Audio Device class
specification version 1.0
01 String descriptor index describes manufacturer
02 String descriptor index describes product
03 String descriptor index displays device serial no.
01 Configuration number = 1
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