WM8758 datasheet(49/90 Pages) WOLFSON

49 / 90 page

Production Data

WM8758B

PD, Rev 4.4, January 2012

3D STEREO ENHANCEMENT

The WM8758B has a digital 3D enhancement option to increase the perceived separation between

the left and right channels. Selection of 3D for record or playback is controlled by register bit

EQ3DMODE. Switching this bit from record to playback or from playback to record may only be done

when ADC and DAC are disabled. The WM8758B control interface will only allow EQ3DMODE to be

changed when ADC and DAC are disabled (ie ADCENL = 0, ADCENR = 0, DACENL = 0 and

DACENR = 0).

The DEPTH3D setting controls the degree of stereo expansion.

When 3D enhancement is used, it may be necessary to attenuate the signal by 6dB to avoid limiting.

In ADC low power mode (See Power Management section), the equaliser and 3D cannot be used. To

enable 3D enhancement and 5-band EQ operation, set M128ENB = 1.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R41 (29h)

3D Control

3:0

DEPTH3D[3:0]

0000

Stereo depth

0000 = 0% (minimum 3D effect)

0001 = 6.67%

....

1110 = 93.3%

1111 = 100% (maximum 3D effect)

Table 31 3D Stereo Enhancement Function

ANALOGUE OUTPUTS

The WM8758B has three sets of stereo analogue outputs. These are:



LOUT1 and ROUT1 which can be used as headphone or line drivers.



LOUT2 and ROUT2 – which can be used as headphone or line drivers.



OUT3 and OUT4 – can be configured as a stereo line out (OUT3 is left output and

OUT4 is right output). OUT4 can also be used to provide a mono mix of left and

right channels.

The outputs LOUT2 and ROUT2 are powered from AVDD2 and are capable of driving a 1V rms

signal (AVDD1/3.3).

LOUT1, ROUT1, OUT3 and OUT4 are powered from AVDD1.

LOUT1, ROUT1, LOUT2 and ROUT2 have individual analogue volume PGAs with -57dB to +6dB

gain ranges.

There are four output mixers in the output signal path, the left and right channel mixers which control

the signals to headphone (and optionally the line outputs) and also dedicated OUT3 and OUT4

mixers.

LEFT AND RIGHT OUTPUT CHANNEL MIXERS

The left and right output channel mixers are shown in Figure 24. These mixers allow the ADC bypass

and the DAC left and right channels to be combined as desired. This allows a mono mix of the DAC

channels to be performed as well as mixing in speech from the input bypass path.

The bypass inputs have individual volume control from -15dB to +6dB and the DAC volume can be

adjusted in the digital domain if required. The output of these mixers is connected to both the stereo

headphone drivers (LOUT1, ROUT1, LOUT2 and ROUT2) and can optionally be connected to the

OUT3 and OUT4 mixers.

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