D+/D–

SEL1 (Pin 9)

2.5 V (Typ)

0 V

Internal Reset

Ready for Setup

Attach

(Connect to USB Bus)

SOF

Ready for Playback

Bus Reset

Set Configuration

SOF

SOF

BPZ

Bus Idle

3.3 V (Typ)

SSPND

700

s

m

Device Setup

1 ms

5 V = V

(Typ)

BUS

V

(Pin 27)

DD

V

L

V

R

OUT

OUT

First Audio Data

Second Audio Data

PCM2903C

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SBFS038A – JUNE 2012 – REVISED SEPTEMBER 2015

9.5.2.4 Interface Number 3

Interface number 3 is the interrupt data-in interface. Alternative setting number 0 is the only possible setting for

interface number 3. Interface number 3 consists of the HID consumer control device and reports the status of

these three key parameters:

•

Mute (0xE209)

•

Volume up (0xE909)

•

Volume down (0xEA09)

9.5.3 Interface Sequence

9.5.3.1 Power On, Attach, and Playback Sequence

The PCM2903C is ready for setup when the reset sequence has finished and the USB bus is attached. In order

to perform certain reset sequences defined in the USB specification, VDD, VCCC, VCCP1, VCCP2, and VCCX must rise

up within 10 ms / 3.3 V. After connection has been established by setup, the PCM2903C 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 PCM2903C stores the first audio packet, which contained 1-ms audio data,

into the internal storage buffer. The PCM2903C starts playing the audio data when detecting the next start of

frame (SOF) packet, as illustrated in Figure 36 and Figure 37.

Figure 36. Attach After Poweron

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