wm8770 Wolfson Microelectronics plc, wm8770 Datasheet - Page 29

• Manufacturer Part Number: wm8770
• Description: 24-bit, 192khz 8-channel Codec With Volume Control
• Manufacturer: Wolfson Microelectronics plc

Production Data
w
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.
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.
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,
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.
11000
Powerdown Control
10101
DAC De-emphasis
Control
11000
Powerdown Control
REGISTER ADDRESS
10011
DAC Channel Control
REGISTER ADDRESS
REGISTER ADDRESS
REGISTER ADDRESS
[3:0] DEEMPH[3:0]
BIT
BIT
BIT
5:2
BIT
0
1
1
DACD[3:0]
LABEL
ATC
PDWN
LABEL
LABEL
LABEL
ADCD
DEFAULT
DEFAULT
DEFAULT
DEFAULT
0
0000
1111
0
1
Attenuator Control Mode:
De-emphasis mode select:
ADC Disable:
Power Down Mode Select:
DAC Disable:
0 : Right channels use Right
1:
0 : Normal Mode
1: De-emphasis Mode
0 : Normal Mode
1: Power Down Mode
0 : Normal Mode
1: Power Down Mode
0 : Normal Mode
1: Power Down Mode
attenuations
Right Channels use Left
Attenuations
DESCRIPTION
DESCRIPTION
DESCRIPTION
DESCRIPTION
PD Rev 4.2 March 2008
WM8770
29