WM8776 datasheet(25/55 Pages) WOLFSON

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WM8776

PP Rev 1.91 June 2004

ADC OVERSAMPLING RATE SELECT

For ADC operation at 96kHz it is recommended that the user set the ADCOSR bit. This

changes the ADC signal processing oversample rate to 64fs.

BIT

LABEL

DEFAULT

DESCRIPTION

R12 (0Ch)

0001100

ADC Oversampling Rate

ADCOSR

ADC oversampling rate select

0: 128x oversampling

1: 64x oversampling

MUTE MODES

Setting MUTE for the DAC will apply a ‘soft’ mute to the input of the digital filters of the

channel muted.

BIT

LABEL

DEFAULT

DESCRIPTION

R8 (08h)

0001000

DAC Mute

DMUTE

DAC Soft Mute select

0 : Normal Operation

1: Soft mute enabled

Figure 21 Application and Release of Soft Mute

Figure 21 shows the application and release of DMUTE whilst a full amplitude sinusoid is

being played at 48kHz sampling rate. When DMUTE (lower trace) is asserted, the output

(upper trace) begins to decay exponentially from the DC level of the last input sample. The

output will decay towards VMID with a time constant of approximately 64 input samples. If

DMUTE is applied to both channels for 1024 or more input samples the DAC will be muted if

IZD is set. When DMUTE is de-asserted, the output will restart immediately from the current

input sample.

Note that all other means of muting the DAC: setting the PL[3:0] bits to 0, setting the PDWN

bit or setting attenuation to 0 will cause much more abrupt muting of the output.

-2.5

-2

-1.5

-1

-0.5

0.5

1.5

0.001

0.002

0.003

0.004

0.005

0.006

Time(s)

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