PCM2704CDB.B datasheet(21/53 Pages) TI2

21 / 53 page

PCM2704C, PCM2705C, PCM2706C, PCM2707C

www.ti.com

SBFS036B – MAY 2015 – REVISED AUGUST 2015

9.3.4 Digital Audio Interface: S/PDIF Output

The PCM2704C/5C/6C/7C employ S/PDIF output. Isochronous-out data from the host are encoded to S/PDIF

output DOUT, as well as to DAC analog outputs VOUTL and VOUTR. The interface format and timing follow the

IEC-60958 standard. Monaural data are converted to the stereo format at the same data rate. S/PDIF output is

not supported in the I2S I/F enable mode. The implementation of this feature is optional.

NOTE

It is the responsibility of the user to determine whether or not to implement this feature in

the end application.

9.3.4.1 Channel Status Information

Channel status information is fixed, and includes consumer application, PCM mode, copyright, and digital/digital

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

according to the data received through the USB.

9.3.4.2 Copyright Management

Digital audio data output is always encoded as original with SCMS control. Only one generation of digital

duplication is allowed.

9.3.5 Digital Audio Interface: I2S Interface Output (PCM2706C/7C)

The PCM2706C and PCM2707C can support the I2S interface, which is enabled by the FSEL pin (pin 9). In the

I2S interface-enabled mode, pins 4, 18, 19, 5, and 17 are assigned as DIN, SYSCK, BCK, LRCK, and DOUT,

respectively. These pins provide digital output/input data in the 16-bit I2S format, which is also accepted by the

internal DAC. Figure 1, Figure 2, and Figure 3 show the I2S interface format and timing. Audio Interface Timing

Characteristics and Audio Clock Timing Characteristics list the audio interface timing and audio clock timing

characteristics, respectively.

9.3.6 Descriptor Data Modification

The descriptor data can be modified through the I2C port by external ROM (PCM2704C/6C) or through the SPI

port by an SPI host such as an MCU (PCM2705C/7C) under a particular configuration of the PSEL and HOST

pins. Setting both the PSEL and the HOST pins high is necessary to modify the descriptor data; the D+ pin

pullup resistor must not be activated before programming the descriptor data through the external ROM or SPI

port is completed. The descriptor data must be sent from an external ROM to the PCM2704C/6C or from the SPI

host to the PCM2705C/7C in LSB first format, with a specified byte order. Additionally, the power attribute and

max power contents must be consistent with the PSEL setting and the power usage from the USB VBUS of the

end application. Therefore, the device does not support descriptor data modification in self-powered configuration

(PSEL = low).

9.3.7 External ROM Descriptor (PCM2704C/6C)

The PCM2704C/6C support an external ROM interface to override internal descriptors. Pin 3 (for the

PCM2704C) or pin 15 (for the PCM2706C) is assigned as DT (serial data), and pin 2 (for the PCM2704C) or pin

14 (for the PCM2706C) is assigned as CK (serial clock) of the I2C interface when using the external ROM

descriptor. Descriptor data are transferred from the external ROM to the PCM2704C/6C through the I2C interface

the first time when the device is activated after a power-on reset. Before completing a read of the external ROM,

the PCM2704C/6C reply with NACK for any USB command request from the host to the device itself. The

descriptor data, which can be in the external ROM, must meet these parameters:

•

String descriptors must be described in ANSI ASCII code (1 byte for each character).

•

String descriptors are converted automatically to unicode strings for transmission to the host.

•

The device address of the external ROM is fixed as 0xA0.

The data bits must be sent from LSB to MSB on the I2C bus. This condition means that each byte of data must

be stored with its bits in reverse order. A read operation is performed at a frequency of XTI/384 (approximately

30 kHz). The power attribute and max power contents must be consistent with the end application circuit

configuration (the PSEL setting and the actual power usage from VBUS of the USB connector); otherwise, it may

cause improper or unexpected PCM2704C/6C operation.

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Product Folder Links: PCM2704C PCM2705C PCM2706C PCM2707C

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