WM8951L datasheet(25/42 Pages) WOLFSON

25 / 42 page

Production Data

WM8951

PD Rev 4.1 December 2007

Figure 21 Master Mode

As a slave device the WM8951L sequences the data transfer (ADCDAT) over the digital audio

interface in response to the external applied clocks (BCLK, ADCLRC). This is illustrated in Figure 22.

Figure 22 Slave Mode

Note that the WM8951L relies on controlled phase relationships between audio interface BCLK, and

the master MCLK or CLKOUT. To avoid any timing hazards, refer to the timing section for detailed

information.

AUDIO DATA SAMPLING RATES

The WM8951L provides for two modes of operation (normal and USB) to generate the required ADC

sampling rates. Normal and USB modes are programmed under software control according to the

table below.

In Normal mode, the user controls the sample rate by using an appropriate MCLK or crystal

frequency and the sample rate control register setting. The WM8951L can support sample rates from

8ks/s up to 96ks/s.

In USB mode, the user must use a fixed MLCK or crystal frequency of 12MHz to generate sample

rates from 8ks/s to 96ks/s. It is called USB mode since the common USB (Universal Serial Bus)

clock is at 12MHz and the WM8951L can be directly used within such systems. WM8951L can

generate all the normal audio sample rates from this one Master Clock frequency, removing the need

for different master clocks or PLL circuits.

BCLK

ADCDAT

ADCLRC

WM8951

ADC

DSP

ENCODER/

DECODER

BCLK

ADCDAT

ADCLRC

WM8951

ADC

DSP

ENCODER/

DECODER

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