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AnalogOut

AnalogIn

Default End-Point

End-Point#2

(IF#1)

AudioStreaming Interface

End-Point#0

End-Point#4

(IF#2)

AudioStreaming Interface

End-Point#5

(IF#3)

HIDInterface

IT

TID1

FU

UID3

OT

TID5

OT

TID2

IT

TID4

Standard AudioControlInterface(IF#0)

PCM2900/2902

M0024-03

Interface #0

PCM2900

PCM2902

SLES035E – MARCH 2007 – REVISED MARCH 2008

Figure 31. USB Audio Function Topology

Interface #0 is defined as the control interface. Alternative setting #0 is the only possible setting for interface #0.

Alternative setting #0 describes the standard audio control interface. A terminal constructs the audio control

interface. The PCM2900/2902 has five terminals as follows:

• Input terminal (IT #1) for isochronous-out stream

• Output terminal (OT #2) for audio analog output

• Feature unit (FU #3) for DAC digital attenuator

• Input terminal (IT #4) for audio analog input

• Output terminal (OT #5) for isochronous-in stream

Input terminal #1 is defined as USB stream (terminal type 0x0101). Input terminal #1 can accept 2-channel audio

streams constructed by left and right channels. Output terminal #2 is defined as a speaker (terminal type

0x0301). Input terminal #4 is defined as a microphone (terminal type 0x0201). Output terminal #5 is defined as a

USB stream (terminal type 0x0101). Output terminal #5 can generate 2-channel audio streams constructed by

left and right channels. Feature unit #3 supports the following sound control features.

• Volume control

• Mute control

The built-in digital volume controller can be manipulated by an audio class specific request from 0 dB to -64 dB

Copyright © 2007–2008, Texas Instruments Incorporated

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Product Folder Link(s): PCM2900 PCM2902