WM8740

Advanced Information

WOLFSON MICROELECTRONICS LTD

AI Rev 1.7 July 2000

12

X[7:0]

ATTENUATION LEVEL

00(hex)

-

∞dB (mute)

01(hex)

-127.0dB

::

::

FD(hex)

-1.0dB

FE(hex)

-0.5dB

FF(hex)

0.0dB

Table 7 Attenuation Control Level

Bit 2 in Reg3 is used to control the attenuator (ATC). When ATC is “high”, the attenuation data

loaded in program register 0 is used for both the left and the right channels. When ATC is low, the

attenuation data for each register is applied separately to left and right channels.

SOFT MUTE

MUT

(REG2, B0)

L

Soft Mute off (normal operation)

H

Soft Mute on (no output)

Table 8 Soft Mute

Setting MUT causes the attenuation to ramp from the current value down to 00. The values held in

the attenuation registers are unchanged. When MUT is reset the attenuation will ramp back up to the

previous value. The ramp rate is 128/fs s/0.5dB step.

DIGITAL DE-EMPHASIS

DEM

(REG2, B1)

L

De-emphasis off

H

De-emphasis on

Table 9 Digital De-Emphasis

DAC OPERATION ENABLE

OPE

(REG2,B2)

L

Normal operation

H

DAC output forced to bipolar zero,

irrespective of input data.

Table 10 DAC Operation Enable

AUDIO DATA INPUT FORMAT

I2S

(REG3, B0)

IW1

(REG2, B4)

IW0

(REG2, B3)

AUDIO INTERFACE

00

0

16-bit standard right justified

00

1

20-bit standard right justified

01

0

24-bit standard right justified

01

1

24-bit left justified (MSB first)

10

0

16-bit I

10

1

24-bit I

11

0

20-bit I

11

1

20-bit left justified (MSB first)

Table 11 Audio Data Input Format