wm8742 Wolfson Microelectronics plc, wm8742 Datasheet - Page 29

• Manufacturer Part Number: wm8742
• Description: 24-bit 192khz Dac With Advanced Digital Filtering
• Manufacturer: Wolfson Microelectronics plc

Production Data
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LRCLK POLARITY
In left justified, right justified or I
bit is set high, the expected polarity of LRCLK will be the opposite of that shown in Figure 14, Figure
15 and Figure 16. If this feature is used as a means of swapping the left and right channels, a 1
sample phase difference will be introduced.
Table 17 LRCLK Polarity Control
In DSP modes, the LRP register bit is used to select between DSP mode A and B (see Figure 17 and
Figure 18).
Table 18 DSP Format Control
BCLK / DSDCLK64 POLARITY
In PCM mode, LRCLK and DIN are sampled on the rising edge of BCLK by default, and should ideally
change on the falling edge. Data sources which change LRCLK and DIN on the rising edge of BCLK
can be supported by setting the BCP register bit. Setting BCP to 1 inverts the polarity of BCLK to the
inverse of that shown in Figure 14, Figure 15, Figure 16, Figure 17 and Figure 18.
In DSD mode, DSDL and DSDR inputs are sampled a fixed delay after a falling 64fs clock edge.
When BCP is set in DSD mode, DSDL and DSDR are sampled a fixed delay after a rising 64fs clock
edge.
Table 19 BCLK Polarity Control
OVERSAMPLING RATE CONTROL
The user has control of the oversampling ratio of the WM8742, and can set to the device to operate in
low, medium or high rate modes. For correct operation of the digital filtering and other processing on
the WM8742, the user must ensure the correct value of OSR[1:0] is set at all times.
Table 20 Oversampling Rate Control
REGISTER ADDRESS
REGISTER ADDRESS
REGISTER ADDRESS
REGISTER ADDRESS
Mode Control 1
Format Control
Format Control
Format Control
07h
05h
05h
05h
R7
R5
R5
R5
[6:5]
BIT
BIT
BIT
BIT
4
4
5
2
S modes, the LRP register bit controls the polarity of LRCLK. If this
OSR[1:0]
LABEL
LABEL
LABEL
LABEL
BCP
LRP
LRP
DEFAULT
DEFAULT
DEFAULT
DEFAULT
00
0
0
0
BCLK / DSD64CLK polarity select:
0 = normal polarity
1 = inverted polarity
Oversampling Rate Selection
00 = Low rate (32/44.1/48kHz)
01 = Medium rate (96kHz)
10 = High rate (192kHz)
11 = Unused
0 = normal LRCLK polarity
1 = inverted LRCLK polarity
0 = DSP mode A
1 = DSP mode B
LRCLK polarity select:
DSP format select:
DESCRIPTION
DESCRIPTION
DESCRIPTION
DESCRIPTION
PD, Rev 4.2, August 2009
WM8742
29