D+/D-

2.5 V (Typ)

0 V

Internal Reset

Ready for Setup

SOF

Ready for Playback

Bus Reset

Set Configuration

SOF

SOF

BPZ

Bus Idle

5 V (Typ)

SSPND

700 s

m

Device Setup

1 ms

V

(Pin 3)

BUS

V

L

V

R

OUT

OUT

First Audio Data

Second Audio Data

D+/D-

Audio Data

Audio Data

Last Audio Data

Detach

SOF

SOF

SOF

SOF

SOF

1 ms

V

(Pin 3)

BUS

V

L

V

R

OUT

OUT

PCM2900C

PCM2902C

SBFS039

– SEPTEMBER 2011

www.ti.com

INTERFACE SEQUENCE

Power On, Attach, and Playback Sequence

The PCM2900C/2902C is ready for setup when the reset sequence has finished and the USB bus is attached.

After connection has been established by setup, the PCM2900C/2902C is ready to accept USB audio data.

While waiting, the audio data (idle state) and analog output are set to bipolar zero (BPZ).

When receiving the audio data, the PCM2900C/2902C stores the first audio packet, which contains 1-ms audio

data, into the internal storage buffer. The PCM2900C/2902C starts to play the audio data when detecting the

next start of frame (SOF) packet, as illustrated in Figure 32.

Figure 32. Initial Sequence

Play, Stop, and Detach Sequence

When the host finishes or aborts playback, the PCM2900C/2902C stops playing after the last audio data have

played, as shown in Figure 33.

Figure 33. Play, Stop, and Detach Sequence

22

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Copyright

© 2011, Texas Instruments Incorporated

Product Folder Link(s): PCM2900C PCM2902C