WM8711 Wolfson Microelectronics Ltd., WM8711 Datasheet - Page 21

• Manufacturer Part Number: WM8711
• Description: Internet Audio DAC With Integrated Headphone Driver
• Manufacturer: Wolfson Microelectronics Ltd.

WM8711
AUDIO DATA SAMPLING RATES
WOLFSON MICROELECTRONICS LTD
As a master mode device the WM8711 controls the sequencing of data transfer (DACDAT) and
output of clocks (BCLK, DACLRC) over the digital audio interface. It uses the timing generated from
the MCLK input as the reference for the clock and data transitions. This is illustrated in Figure 17.
DACDAT is always an input to the WM8711 independent of master or slave mode.
Figure 17 Master Mode
As a slave device the WM8711 sequences the data transfer (DACDAT) over the digital audio
interface in response to the external applied clocks (BCLK, DACLRC). This is illustrated in Figure 18.
Figure 18 Slave Mode
Note that the WM8711 relies on controlled phase relationships between audio interface BCLK,
DACLRC and the master MCLK or CLKOUT. To avoid any timing hazards, refer to the timing section
for detailed information.
The WM8711 provides for two modes of operation (normal and USB) to generate the required DAC
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 frequency and the
sample rate control register setting. The WM8711 can support sample rates from 8ks/s up to 96ks/s.
In USB mode, the user must use a fixed MLCK 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 WM8711 can be directly used within such systems. WM8711 can generate all the
normal audio sample rates from this one Master Clock frequency, removing the need for different
master clocks or PLL circuits.
WM8711
WM8711
DAC
DAC
DACLRC
DACDAT
DACLRC
DACDAT
BCLK
BCLK
DECODER
DECODER
DSP
DSP
PP Rev 1.2 November 2000
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