wm8742 Wolfson Microelectronics plc, wm8742 Datasheet - Page 30

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

WM8742
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MCLK/LRCLK RATIO CONTROL (NORMAL PCM MODE)
The ratio of MCLK/LRCLK can be programmed directly or auto-detected.
Table 21 MCLK/LRCLK Ratio Control (Normal PCM Mode)
8FS Mode allows the use of custom digital filters by bypassing the WM8742 internal digital filters.
When MODE8X is set, the PCM data input to the WM8742 is applied only to the digital volume control
and then the analogue section of the DAC system, bypassing the digital filters.
Table 22 8FS Mode Control
MCLK/LRCLK RATIO CONTROL (8FS MODE)
In 8FS mode the choice of clock ratios and sampling rates is limited – see Table 12 for details.
Autodetect of MCLK/LRCLK ratio is not available in 8FS mode and must be set manually by the user
for correct operation.
Table 23 MCLK/LRCLK Ratio Control (8FS Mode)
ATTENUATION CONTROL
Each DAC channel can be attenuated digitally before being applied to the digital filter. Attenuation is
set to 0dB by default but can be set between 0dB and -127.5dB in 0.125dB steps using the ten
attenuation control bits LAT[4:0], LAT[9:5], RAT[4:0] and RAT[9:5].
All attenuation registers are double latched allowing new values to be pre-latched to both channels
before being updated synchronously. Setting the UPDATE bit on any attenuation write will cause all
pre-latched values to be immediately applied to the DAC channels.
8FS MODE
REGISTER ADDRESS
REGISTER ADDRESS
REGISTER ADDRESS
Mode Control 1
Mode Control 1
Format Control
07h
07h
07h
R7
R7
R7
[4:2]
[4:2]
BIT
BIT
BIT
7
MODE8X
SR[3:0]
SR[2:0]
LABEL
LABEL
LABEL
DEFAULT
DEFAULT
DEFAULT
000
000
0
MCLK to LRCLK sampling rate ratio
control (Normal PCM Mode):
000 = auto detect sample rate
001 = 128fs
010 = 192fs
011 = 256fs
100 = 384fs
101 = 512fs
110 = 768fs
111 = reserved
8FS mode select:
0 = Normal operation
1 = 8FS mode (digital filters
bypassed)
MCLK to LRCLK sampling rate ratio
control (8FS Mode):
000 = reserved
001 = 512fs
010 = 768fs
011 to 111 = reserved
DESCRIPTION
DESCRIPTION
DESCRIPTION
PD, Rev 4.2,August 2009
Production Data
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