PCM1793

SLES076A − MARCH 2003 − REVISED JANUARY 2004

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AUDIO DATA INTERFACE

Audio Serial Interface

The audio interface port is a 3-wire serial port. It includes LRCK (pin 1), BCK (pin 2), and DATA (pin 3). BCK is the

serial audio bit clock, and it is used to clock the serial data present on DATA into the serial shift register of the audio

interface. Serial data is clocked into the PCM1793 on the rising edge of BCK. LRCK is the serial audio left/right word

clock.

The PCM1793 requires the synchronization of LRCK and the system clock, but does not need a specific phase

relation between LRCK and the system clock.

If the relationship between LRCK and the system clock changes more than

±6 BCK, internal operation is initialized

system clock is completed.

PCM Audio Data Formats and Timing

left-justified. The data formats are shown in Figure 26. Data formats are selected using the format bits,

FMT2 (pin 28), FMT1 (pin27), and FMT0 (pin26) as shown in Table 2. All formats require binary 2s complement,

MSB-first audio data. Figure 25 shows a detailed timing diagram for the serial audio interface.

Table 2. Audio Data Format Selection

FMT2

PIN 28

FMT1

PIN 27

FMT0

PIN 26

FORMAT

LOW

LOW

LOW

16-bit standard format, right-justified

LOW

LOW

HIGH

20-bit standard format, right-justified

LOW

HIGH

LOW

24-bit standard format, right-justified

LOW

HIGH

HIGH

24-bit MSB-first, left-justified format

HIGH

LOW

LOW

16-bit I2S format

HIGH

LOW

HIGH

24-bit I2S format

HIGH

HIGH

LOW

Reserved

HIGH

HIGH

HIGH

Reserved