WM8994ECSSLASHR datasheet(99/363 Pages) CIRRUS

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WM8994

Rev 4.6

AIF1 - INPUT PATH SOFT MUTE CONTROL

The WM8994 provides a soft mute function for each of the AIF1 interface input paths. When the soft-

mute function is selected, the WM8994 gradually attenuates the associated signal paths until the path

is entirely muted.

When the soft-mute function is de-selected, the gain will either return instantly to the digital gain

setting, or will gradually ramp back to the digital gain setting, depending on the applicable

_UNMUTE_RAMP register field.

The mute and un-mute ramp rate is selectable between two different rates.

The AIF1 input paths are soft-muted by default. To play back an audio signal, the soft-mute must first

be de-selected by setting the applicable Mute bit to 0.

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

R1056 (0420h)

AIF1 DAC1

Filters (1)

AIF1DAC1_

MUTE

AIF1DAC1 input path (AIF1, Timeslot 0) Soft

Mute Control

0 = Un-mute

1 = Mute

AIF1DAC1_

MUTERAT

AIF1DAC1 input path (AIF1, Timeslot 0) 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.)

AIF1DAC1_

UNMUTE_

RAMP

AIF1DAC1 input path (AIF1, Timeslot 0)

Unmute Ramp select

0 = Disabling soft-mute (AIF1DAC1_MUTE=0)

will cause the volume to change immediately to

AIF1DAC1L_VOL and AIF1DAC1R_VOL

settings

1 = Disabling soft-mute (AIF1DAC1_MUTE=0)

will cause the DAC volume to ramp up

gradually to the AIF1DAC1L_VOL and

AIF1DAC1R_VOL settings

WM8994ECS/R Datenblatt(PDF) 99 Page - Cirrus Logic

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