Pre-Production

WM8501

w

PP Rev 3.1 May 2006

11

RIGHT JUSTIFIED MODE

The WM8501 supports word lengths of 16-bits in right justified mode.

In right justified mode, the digital audio interface receives data on the DIN input. Audio Data is

time multiplexed with LRCLK indicating whether the left or right channel is present. LRCLK is also

used as a timing reference to indicate the beginning or end of the data words.

In right justified mode, the minimum number of BCLKs per LRCLK period is 2 times the selected

word length. LRCLK must be high for a minimum of word length BCLKs and low for a minimum of

word length BCLKs. Any mark to space ratio on LRCLK is acceptable provided the above

requirements are met.

In right justified mode, the LSB is sampled on the rising edge of BCLK preceding a LRCLK

transition. LRCLK is high during the left samples and low during the right samples.

Figure 4 Right Justified Mode Timing Diagram

DSP MODE

A DSP compatible, time division multiplexed format is also supported by the WM8501. This

format is of the type where a ‘synch’ pulse is followed by two data words (left and right) of

predetermined word length. (16-bits). The ‘synch’ pulse replaces the normal duration LRCLK, and

DSP mode is auto-detected by the shorter than normal duration of the LRCLK. If LRCLK is of 4

BCLK or less duration, the DSP compatible format is selected. Mode A and Mode B clock formats

are supported, selected by the state of the FORMAT pin.

Figure 5 DSP Mode A Timing

LRCLK

BCLK

DIN

Input Word Length (16 bits)

1/fs

LEFT CHANNEL

16

2

1

15

LSB

MSB

16

2

1

15

RIGHT CHANNEL

NO VALID DATA

1 BCLK

1 BCLK

max 4 BCLK's