WM8770 datasheet(29/52 Pages) WOLFSON

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Production Data

WM8770

PD Rev 4.1 June 2005

DE-EMPHASIS MODE

A digital De-emphasis filter may be applied to each DAC channel. The De-emphasis filter for each

stereo channel is enabled under the control of DEEMP[3:0]. DEEMP[0] enables the de-emphasis

filter for channel 1, DEEMP[1] enables the de-emphasis filter for channel 2, DEEMP[2] enables the

de-emphasis filter for channel 3 and DEEMP[3] enables the de-emphasis filter for channel 4.

BIT

LABEL

DEFAULT

DESCRIPTION

10101

DAC De-emphasis

Control

[3:0]

DEEMPH[3:0]

0000

De-emphasis mode select:

0 : Normal Mode

1: De-emphasis Mode

Refer to Figure 34, Figure 35, Figure 36, Figure 37, Figure 38 and Figure 39 for details of the De-

Emphasis modes at different sample rates.

POWERDOWN MODE AND ADC/DAC DISABLE

Setting the PDWN register bit immediately powers down the WM8770, including the references,

overriding all other powerdown control bits. All trace of the previous input samples are removed, but

all control register settings are preserved. When PDWN is cleared the digital filters will be

reinitialised. It is recommended that the 8-channel input mux and buffer, ADC, DAC and output

mixers and EVRs are powered down before setting PDWN.

BIT

LABEL

DEFAULT

DESCRIPTION

11000

Powerdown Control

PDWN

Power Down Mode Select:

0 : Normal Mode

1: Power Down Mode

The ADC and DACs may also be powered down by setting the ADCD and DACD disable bits. Setting

ADCD will disable the ADC and select a low power mode. The ADC digital filters will be reset and will

reinitialise when ADCD is reset. Each Stereo DAC channel has a separate disable DACD[3:0].

Setting DACD for a channel will disable the DACs and select a low power mode. Resetting DACD will

reinitialise the digital filters. DACD[0] disbles DAC1, DACD[1] disables DAC2, DACD[2] disables

DAC3 and DACD[3] disables DAC4,

BIT

LABEL

DEFAULT

DESCRIPTION

ADCD

ADC Disable:

0 : Normal Mode

1: Power Down Mode

11000

Powerdown Control

5:2

DACD[3:0]

1111

DAC Disable:

0 : Normal Mode

1: Power Down Mode

ATTENUATOR CONTROL MODE

Setting the ATC register bit causes the left channel attenuation settings to be applied to both left and

right channel DACs from the next audio input sample. No update to the attenuation registers is

required for ATC to take effect.

BIT

LABEL

DEFAULT

DESCRIPTION

10011

DAC Channel Control

ATC

Attenuator Control Mode:

0 : Right channels use Right

attenuations

Right Channels use Left

Attenuations

WM8770 Datasheet(PDF) 29 Page - Wolfson Microelectronics plc

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