WM8972LEFLSLASHR datasheet(23/49 Pages) WOLFSON

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Preliminary Technical Data

WM8972L

PTD Rev 2.2 June 2004

DIGITAL TO ANALOGUE CONVERTER (DAC)

After passing through the graphic equaliser filters, digital ‘de-emphasis’ can be applied to the audio

data if necessary (e.g. when the data comes from a CD with pre-emphasis used in the recording).

De-emphasis filtering is available for sample rates of 48kHz, 44.1kHz and 32kHz.

The WM8972L also has a Soft Mute function, which gradually attenuates the volume of the digital

signal to zero. When removed, the gain will ramp back up to the digital gain setting. This function is

enabled by default. To play back an audio signal, it must first be disabled by setting the DACMU bit

to zero.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

2:1

DEEMP

[1:0]

De-emphasis Control

11 = 48kHz sample rate

10 = 44.1kHz sample rate

01 = 32kHz sample rate

00 = No De-emphasis

R5 (05h)

ADC and DAC

Control

DACMU

Digital Soft Mute

1 = mute

0 = no mute (signal active)

Table 12 DAC Control

The digital audio data is converted to oversampled bit streams in the on-chip, true 24-bit digital

interpolation filters. The bitstream data enters two multi-bit, sigma-delta DACs, which convert them to

high quality analogue audio signals. The multi-bit DAC architecture reduces high frequency noise and

sensitivity to clock jitter. It also uses a Dynamic Element Matching technique for high linearity and

low distortion.

The DAC output defaults to non-inverted. Setting DACINV will invert the DAC output phase on both

left and right channels.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R23 (17h)

Additional

Control (1)

DACINV

DAC phase invert

0 : non-inverted

1 : inverted

Table 13 Phase Invert Select

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