Production Data
DACLRC
BCLK
WM8721 / WM8721L
All four of these modes are MSB first and operate with data 16 to 32 bits, except in right
justified mode where 32 bit data is not supported.
The digital audio interface receives the digital audio data for the internal DAC digital filters on the
DACDAT input. DACDAT is the formatted digital audio data stream output to the DAC digital filters
with left and right channels multiplexed together. DACLRC is an alignment clock that controls
whether Left or Right channel data is present on DACDAT. DACDAT and DACLRC are synchronous
with the BCLK signal with each data bit transition signified by a BCLK high to low transition.
DACDAT is always an input. BCLK and DACLRC are either outputs or inputs depending whether the
device is in master or slave mode. Refer to the MASTER/SLAVE OPERATION section
There are four digital audio interface formats accommodated by the WM8721. These are shown in
the figures below. Refer to the Electrical Characteristic section for timing information.
Left Justified mode is where the MSB is available on the first rising edge of BCLK following a
DACLRC transition.
1/fs
LEFT CHANNEL
RIGHT CHANNEL
DACDAT
123
MSB
n-2 n-1 n
LSB
123
MSB
n-2 n-1 n
LSB
Figure 12 Left Justified Mode
I2S mode is where the MSB is available on the 2nd rising edge of BCLK following a DACLRC
transition.
DACLRC
BCLK
DACDAT
LEFT CHANNEL
1/fs
RIGHT CHANNEL
1 BCLK
123
MSB
n-2 n-1 n
LSB
1 BCLK
123
MSB
n-2 n-1 n
LSB
Figure 13 I2S Mode
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PD Rev 4.0 November 2004
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