WM8746 Wolfson Microelectronics plc, WM8746 Datasheet - Page 13

• Manufacturer Part Number: WM8746
• Description: 24-bit, 192khz 6-channel Dac With Volume Control
• Manufacturer: Wolfson Microelectronics plc

WM8746
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DSP MODE B
In DSP mode B, the first bit is sampled on the BCKIN edge which detects a low to high transition on
LRCIN.
Figure 8 DSP Mode B Timing Diagram
In both DSP modes, DAC0 left is always sent first, followed immediately by data words for the other 5
channels. No BCKIN edges are allowed between the data words. The word order is DAC0 left, DAC0
right, DAC1 left, DAC1 right, DAC2 left, DAC2 right.
SPLIT RATE MODE
The WM8746 can be used with differing sample rates on the front and rear channels. This allows
extremely high quality audio to be played on the front two channels whilst the other channels use
normal high quality data streams.
This mode will only work with a front data rate of 192kHz and a rear rate of 96kHz but can be used
with all the normal data formats except the two DSP modes and with the system at either 128fs or
192fs see Table 4.
When running in split rate mode all the channels are clocked in using a common BCKIN; the front
channels using LRCIN and all the other channels using LRCIN2 see Figure 9.
Figure 9 Split Rate Audio Mode Timing Diagram
Notes:
1. Figure 9 shows the timing for left justified however this is similar for right justified and I
2. The edges of LRCIN and LRCIN2 must be coincidental.
LRCIN2
BCKIN
BCKIN
DIN1/2
LRCIN
LRCIN
DIN0
DIN0
MSB
1
Input Word Length (IWL)
MSB
MSB
1
1
2
2
2
CHANNEL 0
LEFT CHANNEL
LEFT
n-1
LSB
LSB
LSB
LEFT CHANNEL
n
n
n
1
MSB
1
2
2
CHANNEL 0
RIGHT CHANNEL
RIGHT
n-1
LSB
n
n
CHANNEL 1
1
1/fs
2/fs
MSB
MSB
LEFT
1
1
2
2
2
LEFT CHANNEL
LSB
LSB
CHANNEL 2
n
n
RIGHT CHANNEL
RIGHT
n-1
MSB
1
PD, October 2008, Rev 4.2
n
2
RIGHT CHANNEL
NO VALID DATA
Production Data
LSB
n
2
S.
1
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