PCM2900

PCM2902

SLES035B − MARCH 2002 − REVISED JUNE 2004

www.ti.com

21

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)

PCM2900/2902

Figure 31. USB Audio Function Topology

Interface #0

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 #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.

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

until the volume level has reached the requested value. Each channel can be set for different values. The master