Preliminary Technical Data

WM8737L

w

AI Rev 3.0 May 2004

21

REGISTER

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

0

3DEN

0

3D function enable

0: disable

1: enable

4:1

3DDEPTH[3:0]

0000

Stereo depth

0000: 0% (minimum 3D effect)

0001: 6.67%

....

1110: 93.3%

1111: 100% (maximum 3D effect)

5

3DUC

0

Upper Cut-off frequency

0 = High (2.2kHz at 48kHz sampling)

1 = Low (1.5kHz at 48kHz sampling)

6

3DLC

0

Lower Cut-off frequency

0 = Low (200Hz at 48kHz sampling)

1 = High (500Hz at 48kHz sampling)

R4 (04h)

3D Control

7

DIV2

0

ADC 6dB attenuate enable

0: disabled (0dB)

1: -6dB enabled

Table 11 Stereo Enhancement Control

AUTOMATIC LEVEL CONTROL (ALC)

The WM8737L has an automatic level control that aims to keep a constant recording volume

irrespective of the input signal level. This is achieved by continuously adjusting the PGA gain so that

the signal level at the ADC input remains constant. A digital peak detector monitors the ADC output

and changes the PGA gain if necessary.

hold

time

decay

time

attack

time

input

signal

signal

after

ALC

PGA

gain

ALC

target

level

Figure 8 ALC Operation

The ALC function is enabled using the ALCSEL[1:0] control bits in register R12. When enabled, the

recording volume can be programmed between -3dB and -18dB (relative to ADC full scale) using the

ALCL[3:0] register bits in register R12.

R13 and R14 bits HLD[3:0], DCY[3:0] and ATK[3:0] control the hold, decay and attack times,

respectively: