WM8944BECSSLASHR datasheet(50/165 Pages) CIRRUS

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WM8944B

Rev 4.3

DAC AUTO-MUTE

The DAC digital mute and volume controls are described earlier in Table 26.

The DAC also incorporates an analogue auto-mute, which is enabled by setting DAC_AUTOMUTE.

When the auto-mute is enabled, and a series of 1024 consecutive zero-samples is detected, the DAC

output is muted in order to attenuate noise that might be present in output signal path. The DAC

resumes normal operation as soon as digital audio data is detected.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R21 (15h)

DAC Control 1

DAC_AUTOMUT

DAC Auto-Mute Control

0 = Disabled

1 = Enabled

Table 28 DAC Auto Mute

Note: The DAC_AUTOMUTE bit should not be set when the BEEP generator is used.

DAC SLOPING STOPBAND FILTER

Two DAC filter types are available, selected by the register bit DAC_SB_FLT. When operating at

lower sample rates (e.g. during voice communication) it is recommended that the sloping stopband

filter type is selected (DAC_SB_FLT=1) to reduce out-of-band noise which can be audible at low DAC

sample rates. See “Digital Filter Characteristics” for details of DAC filter characteristics.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R22 (16h)

DAC Control 2

DAC_SB_FLT

Selects DAC filter characteristics

0 = Normal mode

1 = Sloping stopband mode

Table 29 DAC Sloping Stopband Filter

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