WM8741
Production Data
OVERSAMPLING RATE CONTROL
The user has control of the oversampling ratio of the WM8741, and can set to the device to operate
in low, medium or high rate modes. For optimum operation of the digital filtering and other
processing on the WM8741 in PCM hardware mode, the user must ensure the correct value of OSR
is set at all times. Table 47 shows the correct settings:
PIN
NAME
DESCRIPTION
22
OSR/DSDR Oversampling Rate Selection
0 = Low rate (32/44.1/48kHz)
Z = Medium rate (88.2/96kHz)
1 = High rate (176.4/192kHz)
Table 47 OSR/DSDR Hardware Control Pin Function
MUTE PIN
A soft mute can be applied to the WM8741 in the digital domain in all PCM. A logic low on the
MUTEB pin will cause the attenuation to ramp to infinite attenuation at a rate of 1022x(4/fs). Setting
MUTEB high will return the signal gain to its previous value. Figure 26 shows the soft mute
characteristic.
In DSD Direct mode the MUTEB pin controls the analogue mute in the DAC. This analogue mute is
a ‘hard’ mute and is applied and released as soon as the MUTEB pin is toggled.
PIN
NAME
MUTEB/
SDOUT
DESCRIPTION
Mute control
25
0 = Mute on (no output)
1 = Mute off (normal operation
Table 48 MUTEB Hardware Control Pin Function
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
Time (s)
Figure 26 Hardware Control Mode Soft Mute Characteristic
PD, Rev 4.2, October 2009
40
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
