Datasheet

PCM2903C

SBFS038 –JUNE 2012

www.ti.com

Clock and Reset

The PCM2903C requires a 12-MHz (±500 ppm) clock for the USB and audio function, which can be generated

by a built-in crystal oscillator with a 12-MHz crystal resonator or supplied by an external clock. The 12-MHz

crystal resonator must be connected to XTI (pin 21) and XTO (pin 20) with one high (1-MΩ) resistor and two

small capacitors, the capacitance of which depends on the load capacitance of the crystal resonator. If the

external clock is used, the clock must be supplied to XTI, and XTO must be open.

The PCM2903C has an internal power-on reset circuit, which triggers automatically when V

(pin 27) exceeds

2.5 V typical (2.7 V to 2.2 V). Approximately 700 μs is required until internal reset release.

Digital Audio Interface

The PCM2903C employs both S/PDIF input and output. Isochronous-out data from the host are encoded to the

S/PDIF output and the DAC analog output. Input data are selected as either S/PDIF or ADC analog input. When

the device detects an S/PDIF input and successfully locks on the received data, the isochronous-in transfer data

source is automatically selected from S/PDIF itself; otherwise, the data source selected is the ADC analog input.

This feature is a customer option. It is the responsibility of the user to implement this feature.

Supported Input/Output Data

The following data formats are accepted by the S/PDIF input and output. All other data formats are unable to use

S/PDIF.

• 48-kHz 16-bit stereo

• 44.1-kHz 16-bit stereo

• 32-kHz 16-bit stereo

Any mismatch of the sampling rate between the input S/PDIF signal and the host command is not acceptable.

Any mismatch of the data format between the input S/PDIF signal and the host command may cause unexpected

results, with the following exceptions:

• Recording in monaural format from stereo data input at the same data rate

• Recording in 8-bit format from 16-bit data input at the same data rate

A combination of these two conditions is not acceptable.

For playback, all possible data-rate sources are converted to 16-bit stereo format at the same source data rate.

Channel Status Information

The channel status information is fixed as consumer application, PCM mode, copyright, and digital/digital

converter. All other bits are fixed as 0's except for the sample frequency, which is set automatically according to

the data received through the USB.

Isochronous-in data are affected by the serial copy management system (SCMS). When the control bit indicates

that the received digital audio data are original, the input digital audio data are transferred to the host. If the data

are indicated as first generation or higher, the transferred data are routed to the analog input.

Digital audio data output is always encoded as original with SCMS control.

Product Folder Link(s): PCM2903C