WM8994 datasheet(98/359 Pages) WOLFSON

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WM8994

Production Data

PD, April 2012, Rev 4.4

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R1280

(0500h)

AIF2 ADC

Left Volume

AIF2ADC_V

N/A

AIF2ADC output path Volume Update

Writing a 1 to this bit will cause the AIF2ADCL

and AIF2ADCR volume to be updated

simultaneously

7:0

AIF2ADCL_

VOL [7:0]

C0h

(0dB)

AIF2ADC (Left) output path Digital Volume

00h = MUTE

01h = -71.625dB

… (0.375dB steps)

EFh = +17.625dB

(See Table 35 for volume range)

R1281

(0501h)

AIF2 ADC

Right Volume

AIF2ADC_V

N/A

AIF2ADC output path Volume Update

Writing a 1 to this bit will cause the AIF2ADCL

and AIF2ADCR volume to be updated

simultaneously

7:0

AIF2ADCR_

VOL [7:0]

C0h

(0dB)

AIF2ADC (Right) output path Digital Volume

00h = MUTE

01h = -71.625dB

… (0.375dB steps)

EFh = +17.625dB

(See Table 35 for volume range)

Table 42 AIF2 Output Path Volume Control

AIF2 - OUTPUT PATH HIGH PASS FILTER

A digital high-pass filter can be enabled in the AIF2 output paths to remove DC offsets. This filter is

enabled independently in the two AIF2 output channels using the register bits described in Table 43.

The HPF cut-off frequency for the AIF2 channels is set using AIF2ADC_HPF_CUT.

In hi-fi mode, the high pass filter is optimised for removing DC offsets without degrading the bass

response and has a cut-off frequency of 3.7Hz when the sample rate (fs) = 44.1kHz.

In voice modes, the high pass filter is optimised for voice communication; it is recommended to set

the cut-off frequency below 300Hz.

Note that the cut-off frequencies scale with the AIF2 sample rate. (The AIF2 sample rate is set using

the AIF2_SR register, as described in the “Clocking and Sample Rates” section.) See Table 37 for the

HPF cut-off frequencies at all supported sample rates.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R1296 (0510h)

AIF2 ADC

Filters

14:13

AIF2ADC_H

PF_CUT

[1:0]

AIF2ADC output path Digital HPF Cut-Off

Frequency (fc)

00 = Hi-fi mode (fc = 4Hz at fs = 48kHz)

01 = Voice mode 1 (fc = 127Hz at fs = 8kHz)

10 = Voice mode 2 (fc = 130Hz at fs = 8kHz)

11 = Voice mode 3 (fc = 267Hz at fs = 8kHz)

AIF2ADCL_

HPF

AIF2ADC (Left) output path Digital HPF

Enable

0 = Disabled

1 = Enabled

AIF2ADCR_

HPF

AIF2ADC (Right) output path Digital HPF

Enable

0 = Disabled

1 = Enabled

Table 43 AIF2 Output Path High Pass Filter

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