Analog Out

Analog In

Default End-Point

End-Point #2

(IF #1)

Audio Streaming Interface

End-Point #0

End-Point #4

(IF #2)

Audio Streaming Interface

End-Point #5

(IF #3)

HID Interface

IT

TID1

FU

UID3

OT

TID5

OT

TID2

IT

TID4

Standard Audio Control Interface (IF #0)

PCM2903C

www.ti.com

SBFS038A – JUNE 2012 – REVISED SEPTEMBER 2015

The string descriptor contains the information described in Table 3.

Table 3. String Descriptor

Number 0

0x0409

Number 1

BurrBrown from Texas Instruments

Number 2

(1)

Ensure that there are two blank spaces between "Audio" and "CODEC"; copying and pasting will not

transfer the two blank spaces correctly.

9.5.2 Device Configuration

Figure 35 illustrates the USB audio function topology. The PCM2903C has four interfaces. Each interface

consists of alternative settings.

Figure 35. USB Audio Function Topology

9.5.2.1 Interface Number 0

Interface number 0 is the control interface. Alternative setting number 0 is the only possible setting for interface

number 0. Alternative setting number 0 describes the standard audio control interface. The audio control

interface consists of a single terminal. The PCM2903C has the following five terminals:

•

Input terminal (IT number 1) for isochronous-out stream

•

Output terminal (OT number 2) for audio analog output

•

Feature unit (FU number 3) for DAC digital attenuator

•

Input terminal (IT number 4) for audio analog input

•

Output terminal (OT number 5) for isochronous-in stream

Input terminal number 1 is defined as USB stream (terminal type 0x0101). Input terminal number 1 can accept

two-channel audio streams consisting of left and right channels. Output terminal number 2 is defined as a

speaker (terminal type 0x0301). Input terminal number 4 is defined as a line connector (terminal type 0x0603).

Output terminal number 5 is defined as a USB stream (terminal type 0x0101). Output terminal number 5 can

generate two-channel audio streams composed of left and right channel data. Feature unit number 3 supports

the following sound control features:

•

Volume control

•

Mute control

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Product Folder Links: PCM2903C