WM8778 datasheet(27/50 Pages) WOLFSON

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WM8778

PP Rev 1.7 June 2004

ADC MUTE

Each ADC channel also has an individual mute control bit, which mutes the input to the ADC PGA.

By setting the LRBOTH bit (reg22, bit 8) both channels can be muted simultaneously.

BIT

LABEL

DEFAULT

DESCRIPTION

R21 (15h)

0010101

ADC Mute Left

MUTELA

ADC Mute Select

0 : Normal Operation

1: mute ADC left

R21 (15h)

0001111

ADC Mute Right

MUTERA

ADC Mute Select

0 : Normal Operation

1: mute ADC right

DE-EMPHASIS MODE

The De-emphasis filter for the DAC is enabled under the control of DEEMP.

BIT

LABEL

DEFAULT

DESCRIPTION

R9 (09h)

0001001

DAC De-emphasis

Control

DEEMPH

De-emphasis Mode Select:

0 : Normal Mode

1: De-emphasis Mode

Refer to Figure 32, Figure 33, Figure 34, Figure 35, Figure 36 and Figure 37 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 WM8778, including the references,

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

control register settings are preserved. When PDWN is cleared, the digital filters will be re-initialised.

It is recommended that the buffer, ADC and DAC are powered down before setting PDWN.

BIT

LABEL

DEFAULT

DESCRIPTION

R13 (0Dh)

0001101

Powerdown Control

PDWN

Power Down Mode Select:

0 : Normal Mode

1: Power Down Mode

The ADC and DAC may also be powered down by setting the ADCPD and DACPD disable bits.

Setting ADCPD will disable the ADC and select a low power mode. The ADC digital filters will be

reset and will reinitialise when ADCPD is reset. The DAC has a separate disable DACPD. Setting

DACPD will disable the DAC, mixer and output PGAs. Resetting DACPD will reinitialise the digital

filters.

BIT

LABEL

DEFAULT

DESCRIPTION

ADCPD

ADC Powerdown:

0 : Normal Mode

1: Power Down Mode

R13 (0Dh)

0001101

Powerdown Control

DACPD

DAC Powerdown:

0 : Normal Mode

1: Power Down Mode

The analogue audio inputs and outputs can also be individually powered down by setting the relevant

bits in the powerdown register.

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