WM8718

Production Data

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PD Rev 4.1 March 2004

11

The WM8718 will automatically detect when data with a LRCIN period of exactly 32 BCKINs is

sent, and select 16-bit mode - overriding any previously programmed word length. Word length

will revert to a programmed value only if a LRCIN period other than 32 BCKINs is detected.

In DSP early or DSP late mode, the data is time multiplexed onto DIN. LRCIN is used as a frame

sync signal to identify the MSB of the first word. The minimum number of BCKINs per LRCIN

period is 2 times the selected word length. Any mark to space ratio is acceptable on LRCIN

provided the rising edge is correctly positioned. (See Figure 7 and Figure 8)

LEFT JUSTIFIED MODE

In left justified mode, the MSB is sampled on the first rising edge of BCKIN following a LRCIN

transition. LRCIN is high during the left data word and low during the right data word.

LEFT CHANNEL

RIGHT CHANNEL

LRCIN

BCKIN

DIN

1/fs

n

3

2

1

n-2 n-1

LSB

MSB

n

3

2

1

n-2 n-1

LSB

MSB

Figure 4 Left Justified Mode Timing Diagram

RIGHT JUSTIFIED MODE

In right justified mode, the LSB is sampled on the rising edge of BCKIN preceding a LRCIN

transition. LRCIN is high during the left data word and low during the right data word.

LEFT CHANNEL

RIGHT CHANNEL

LRCIN

BCKIN

DIN

1/fs

n

3

2

1

n-2 n-1

LSB

MSB

n

3

2

1

n-2 n-1

LSB

MSB

Figure 5 Right Justified Mode Timing Diagram

I

In I

transition. LRCIN is low during the left data word and high during the right data word.

LEFT CHANNEL

RIGHT CHANNEL

LRCIN

BCKIN

DIN

1/fs

n

3

2

1

n-2 n-1

LSB

MSB

n

3

2

1

n-2 n-1

LSB

MSB

1 BCKIN

1 BCKIN

Figure 6 I