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SERIAL AUDIO DATA INTERFACE

Interface Mode

Data Format

PCM1850A

PCM1851A

SLES173 – MARCH 2006

The PCM1850A/1851A interfaces with the audio system through BCK (pin 2), LRCK (pin 1), and DOUT (pin 3).

The PCM1850A/1851A supports both master and slave modes as interface modes, and they are selected by

mode control via the serial port as shown in Table 4.

In master mode, the PCM1850A/1851A provides the timing for serial audio data communications between the

PCM1850A/1851A and the digital audio processor or external circuit. While in slave mode, the PCM1850A/1851A

receives the timing for data transfer from an external controller.

Table 4. Interface Mode

MD1

MD0

INTERFACE MODE

0

0

0

1

1

0

1

1

Master Mode

In master mode, BCK and LRCK work as output pins, and these pins are controlled by timing which is generated

in the clock and timing control circuit of the PCM1850A/1851A. The frequency of BCK is fixed at 64

× LRCK. A

Slave Mode

In slave mode, BCK and LRCK work as input pins. The PCM1850A/1851A accepts the 64 BCK/LRCK or 48

slave mode.

The PCM1850A/1851A supports four audio data formats in both master and slave modes, and they are selected

by mode control via the serial port as shown in Table 5. Figure 23 illustrates the data formats in both slave and

master modes.

Table 5. Data Format

FORMAT NO.

FMT2

FMT1

FMT0

FORMAT

0

1

0

1

Left-justified, 24-bit

1

1

0

0

2

0

0

0

Right-justified, 24-bit

3

0

1

1

Right-justified, 16-bit

18

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