WM8714

Production Data

w

PD Rev 4.0 November 2004

11

RIGHT JUSTIFIED MODE

The WM8714 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 LRCIN indicating whether the left or right channel is present. LRCIN 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 BCKINs per LRCIN period is 2 times the selected

word length. LRCIN must be high for a minimum of word length BCKINs and low for a minimum of

word length BCKINs. Any mark to space ratio on LRCIN is acceptable provided the above

requirements are met.

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

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

LEFT CHANNEL

RIGHT CHANNEL

LRCIN

BCKIN

DIN

1/fs

16

3

2

1

14

15

LSB

MSB

16

3

2

1

14

15

LSB

MSB

Figure 4 Right Justified Mode Timing Diagram

AUDIO DATA SAMPLING RATES

The master clock for WM8714 supports audio sampling rates from 256fs and 384fs, where fs is

the audio sampling frequency (LRCIN) typically 32kHz, 44.1kHz, 48kHz, and 96kHz. The master

clock is used to operate the digital filters and the noise shaping circuits.

The WM8714 has a master clock detection circuit that automatically determines the relation

between the master clock frequency and the sampling rate (to within +/- 8 master clocks). If there

is a greater than 8 clocks error, the interface shuts down the DAC and mutes the output. The

master clock should be synchronised with LRCIN, although the WM8714 is tolerant of phase

differences or jitter on this clock.

SAMPLING

RATE

MASTER CLOCK

FREQUENCY (MHZ)

(MCLK)

(LRCIN)

256fs

384fs

32kHz

8.192

12.288

44.1kHz

11.2896

16.9340

48kHz

12.288

18.432

96kHz

24.576

1

36.864

1

Table 1 Master Clock Frequencies Versus Sampling Rate

Notes:

1.

96kHz sample rate at either 256fs or 384fs are only supported with 5V supplies.