WM8987LGECOSLASHV datasheet(29/58 Pages) WOLFSON

29 / 58 page

Pre-Production

WM8987L

PP Rev 3.0 January 2007

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 WM8987L also has a Soft Mute function, which gradually attenuates the volume of the digital

signal to zero. When removed, the gain will return to the original 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 19 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.

In normal operation, the left and right channel digital audio data is converted to analogue in two

separate DACs. However, it is also possible to disable one channel, so that the same signal (left or

right) appears on both analogue output channels. Additionally, there is a mono-mix mode where the

two audio channels are mixed together digitally and then converted to analogue using only one DAC,

while the other DAC is switched off. The mono-mix signal can be selected to appear on both

analogue output channels.

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

5:4

DMONOMIX

[1:0]

DAC mono mix

00: stereo

01: mono ((L+R)/2) into DACL, ‘0’ into

DACR

10: mono ((L+R)/2) into DACR, ‘0’ into

DACL

11: mono ((L+R)/2) into DACL and

DACR

R23 (17h)

Additional

Control (1)

DACINV

DAC phase invert

0 : non-inverted

1 : inverted

Table 20 DAC Mono Mix and Phase Invert Select

WM8987LGECO/V Folha de dados(PDF) 29 Page - Wolfson Microelectronics plc

WM8987LGECO/V Folha de dados(HTML) 29 Page - Wolfson Microelectronics plc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58

Folha de dados Download

Ligação URL