Pre-Production

WM8786

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PP Rev 3.0 December 2005

19

MASTER CLOCK AND AUDIO SAMPLE RATES

The master clock (MCLK) is used to operate the digital filters and the noise shaping circuits. The

WM8786 supports a wide range of master clock frequencies, and can generate many commonly

used audio sample rates directly from the master clock. The following tables show the recommended

Master clock frequencies for different sample rates.

In Master Mode, with oversampling ratio = single rate or dual rate, Master clock frequency of 256 is

supported.

MASTER CLOCK FREQUENCY (MHz)

SAMPLING RATE

(LRCLK)

OVERSAMPLING

RATIO

256fs

32kHz

Single Rate

8.192

44.1kHz

Single Rate

11.2896

48kHz

Single Rate

12.288

96kHz

Dual Rate

24.576

Table 6 Master Mode: Recommended Master Clock Frequency Selection

In Master Mode, with oversampling ratio = quad rate, Master clock frequency of 192 is supported.

MASTER CLOCK FREQUENCY (MHz)

SAMPLING RATE

(LRCLK)

OVERSAMPLING

RATIO

128fs

192kHz

Quad Rate

24.576

Table 7 Master Mode: Recommended Master Clock Frequency Selection

The WM8786 automatically detects the audio sample rate, in slave mode.

MASTER CLOCK FREQUENCY (MHz)

SAMPLING RATE

(LRCLK)

OVERSAMPLING

RATIO

128fs

192fs

256fs

384fs

512fs

768fs

32kHz

Single Rate

-

-

8.192

12.288

16.384

24.576

44.1kHz

Single Rate

-

-

11.2896

16.9344

22.5792

33.8688

48kHz

Single Rate

-

-

12.288

18.432

24.576

36.864

96kHz

Dual Rate

-

-

24.576

36.864

-

-

192kHz

Quad Rate

24.576

36.864

-

-

-

-

Table 8 Slave Mode: Recommended Master Clock Frequency Selection

MLCK AND LRCLK PHASE RELATIONSHIP

The WM8786 does not require a specific phase relationship between MLCK and LRCLK. If the

relationship between MCLK and LRCLK changes by more than +/-8 BCLKs in a 64 BLCK frame, the

WM8786 will attempt to re-synchronise During re-synchronisation, data samples may be dropped or

duplicated.