WM8734SEFL Wolfson Microelectronics, WM8734SEFL Datasheet - Page 27

• Manufacturer Part Number: WM8734SEFL
• Description: Audio CODECs Stereo CODEC
• Manufacturer: Wolfson Microelectronics

Specifications of WM8734SEFL

• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Package / Case: QFN-28
• Minimum Operating Temperature: - 25 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

WM8734
AUDIO DATA SAMPLING RATES
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As a master mode device the WM8734 controls the sequencing of data transfer (ADCDAT,
DACDAT) and output of clocks (BCLK, ADCLRC, DACLRC) over the digital audio interface. It uses
the timing generated from either its on-board crystal or the MCLK input as the reference for the clock
and data transitions. This is illustrated in Figure 21. ADCDAT is always an output from and DACDAT
is always an input to the WM8734 independent of master or slave mode.
Figure 21 Master Mode
As a slave device the WM8734 sequences the data transfer (ADCDAT, DACDAT) over the digital
audio interface in response to the external applied clocks (BCLK, ADCLRC, DACLRC). This is
illustrated in Figure 22.
Figure 22 Slave Mode
Note that the WM8734 relies on controlled phase relationships between audio interface BCLK,
DACLRC and the master MCLK. To avoid any timing hazards, refer to the timing section for detailed
information.
The WM8734 provides for two modes of operation (normal and USB) to generate the required DAC
and 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 WM8734 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 WM8734 can be directly used within such systems. WM8734 can
generate all the normal audio sample rates from this one Master Clock frequency, removing the need
for different master clocks or PLL circuits.
WM8734
WM8734
CODEC
CODEC
ADCLRC
ADCDAT
ADCLRC
DACLRC
DACDAT
ADCDAT
DACLRC
DACDAT
BCLK
BCLK
ENCODER/
ENCODER/
DECODER
DECODER
DSP
DSP
PD, Rev 4.3, January 2009
Production Data
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