Pre-Production
WM8786
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.
SAMPLING RATE
(LRCLK)
OVERSAMPLING
RATIO
MASTER CLOCK FREQUENCY (MHz)
256fs
8.192
32kHz
44.1kHz
48kHz
Single Rate
Single Rate
Single Rate
Dual Rate
11.2896
12.288
24.576
96kHz
Table 6 Master Mode: Recommended Master Clock Frequency Selection
In Master Mode, with oversampling ratio = quad rate, Master clock frequency of 192 is supported.
SAMPLING RATE
(LRCLK)
OVERSAMPLING
RATIO
MASTER CLOCK FREQUENCY (MHz)
128fs
192kHz
Quad Rate
24.576
Table 7 Master Mode: Recommended Master Clock Frequency Selection
In Slave Mode, Master clock frequencies of 128fs, 192fs, 256fs, 384fs, 512fs and 768fs are supported..
The WM8786 automatically detects the audio sample rate, in slave mode.
SAMPLING RATE
(LRCLK)
OVERSAMPLING
MASTER CLOCK FREQUENCY (MHz)
RATIO
128fs
192fs
256fs
384fs
512fs
768fs
32kHz
44.1kHz
48kHz
Single Rate
Single Rate
Single Rate
Dual Rate
-
-
8.192
11.2896
12.288
24.576
-
12.288
16.9344
18.432
36.864
-
16.384
24.576
-
-
22.5792
33.8688
-
-
24.576
36.864
96kHz
-
-
-
-
-
-
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.
PP Rev 3.0 December 2005
19
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
