WM8593 datasheet(25/98 Pages) WOLFSON

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WM8593

PP Rev 1.0 January 2007

DIGITAL AUDIO DATA FORMATS

The WM8593 supports a range of common audio interface formats:

•

Left Justified (LJ)

•

Right Justified (RJ)

•

DSP Mode A

•

DSP Mode B

All formats send the MSB first and support word lengths of 16, 20, 24 and 32 bits, with the exception

of 32 bit RJ mode, which is not supported.

Audio data for each stereo channel is time multiplexed with the interface’s left/right clock indicating

whether the left or right channel is present. The left/right clock is also used as a timing reference to

indicate the beginning or end of the data words.

In LJ, RJ and I

2S modes, the minimum number of bit clock periods per left/right clock period is two

times the selected word length. The left/right clock must be high for a minimum of bit clock periods

equivalent to the word length, and low for the same period. For example, for a word length of 24 bits,

the left/right clock must be high for a minimum of 24 bit clock periods and low for a minimum of 24

bit clock periods. Any mark to space ratio is acceptable for the left/right clock provided these

requirements are met.

In DSP modes A and B, left and right channels must be time multiplexed and input on DIN1. LRCLK

is used as a frame synchronisation signal to identify the MSB of the first input word. The minimum

number of bit clock periods per left/right clock period is two times the selected word length. Any

mark to space ratio is acceptable for the left/right clock provided the rising edge is correctly

positioned.

I2S MODE

In I

2S mode, the MSB of input data is sampled on the second rising edge of bit clock following a

left/right clock transition. The MSB of output data changes on the first falling edge of bit clock

following a left/right clock transition, and may be sampled on the next rising edge of bit clock.

Left/right clocks are low during the left channel audio data samples and high during the right channel

audio data samples.

Figure 12 I2S Mode Timing

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