WM8994ECSSLASHR datasheet(104/363 Pages) CIRRUS

104 / 363 page

WM8994

104

Rev 4.6

The soft un-mute would typically be used during playback of audio data so that when the Mute is

subsequently disabled, a smooth transition is scheduled to the previous volume level and pop noise is

avoided. This is desirable when resuming playback after pausing during a track.

The soft un-mute would typically not be required when un-muting at the start of a music file, in order

that the first part of the music track is not attenuated. The instant un-mute behaviour is desirable in

this case, when starting playback of a new track.

See “DAC Soft Mute and Soft Un-Mute” (Figure 30)

for an illustration of the soft mute function.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R1312 (0520h)

AIF2 DAC

Filters (1)

AIF2DAC_M

UTE

AIF2DAC input path Soft Mute Control

0 = Un-mute

1 = Mute

AIF2DAC_M

UTERATE

AIF2DAC input path Soft Mute Ramp Rate

0 = Fast ramp (fs/2, maximum ramp time is

10.7ms at fs=48k)

1 = Slow ramp (fs/32, maximum ramp time is

171ms at fs=48k)

(Note: ramp rate scales with sample rate.)

AIF2DAC_U

NMUTE_RA

AIF2DAC input path Unmute Ramp select

0 = Disabling soft-mute (AIF2DAC_MUTE=0)

will cause the volume to change immediately

to AIF2DACL_VOL and AIF2DACR_VOL

settings

1 = Disabling soft-mute (AIF2DAC_MUTE=0)

will cause the DAC volume to ramp up

gradually to the AIF2DACL_VOL and

AIF2DACR_VOL settings

Table 45 AIF2 Input Path Soft Mute Control

AIF2 - INPUT PATH MONO MIX AND DE-EMPHASIS FILTER

A digital mono mix can be selected on the AIF2 input channels. The mono mix is generated as the

sum of the Left and Right AIF channel data. When the mono mix function is enabled, the combined

mono signal is applied to the Left channel and the Right channel of the AIF2 signal processing and

digital mixing paths. To prevent clipping, 6dB attenuation is applied to the mono mix.

Digital de-emphasis can be applied to the AIF2 input (playback) paths; this is appropriate when the

data source is a CD where pre-emphasis is used in the recording. De-emphasis filtering is available

for sample rates of 48kHz, 44.1kHz and 32kHz. See "Digital Filter Characteristics

” section for details

of de-emphasis filter characteristics.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R1312 (0520h)

AIF2 DAC

Filters (1)

AIF2DAC_M

ONO

AIF2DAC input path Mono Mix Control

0 = Disabled

1 = Enabled

2:1

AIF2DAC_D

EEMP [1:0]

AIF2DAC input path De-Emphasis Control

00 = No de-emphasis

01 = 32kHz sample rate

10 = 44.1kHz sample rate

11 = 48kHz sample rate

Table 46 AIF2 Input Path Mono Mix and De-Emphasis Filter Control

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