Production Data

WM8736

WOLFSON MICROELECTRONICS LTD

PD Rev 2.1 January 2001

13

The master gain register M8 (A[3:0] = 0110) is used to write a gain value to all channels

simultaneously. Bit 8 (LDM) controls the update in the same way as the attenuation registers, and is

to be set to 1 for correct operation in this mode.

LEFT AND RIGHT DAC SOFT MUTE CONTROL

Soft mute is controlled by setting bit MU, register M2:bit 0. A high level on MU (MU = 1) will cause

the output to be muted, the effect of which is to ramp the signal down in the digital domain so that

there is no discernible click. This can be seen in Figure 6 Mute Circuit Operation.

DE-EMPHASIS CONTROL

Bit 1 (DE) in register M2 is used to control digital de-emphasis. A low level on bit 1 (DE = 0) disables

de-emphasis whilst a high level enables de-emphasis (DE = 1). De-emphasis applied to the filters

shapes the frequency response of the digital filter according to the input sample frequency.

LEFT AND RIGHT DAC OPERATION CONTROL

Bit 2 (OPE) in register M2 is used for operation control. With OPE = 0 (default) the device functions

normally. With OPE = 1 the device is disabled and the outputs are held at midrail. Current

consumption of the digital section is minimized, but analogue sections remain active in order to

preserve d.c. levels.

INPUT AUDIO WORD RESOLUTION

WM8736 allows maximum flexibility over the control of the audio data interface, allowing selection of

format type, word length, and sample rates. Bits 3 and 4 of register M2 (IW[1:0]) are used to

determine the input word resolution. WM8736 supports 16-bit, 18-bit, 20-bit and 24-bit formats as

described in Table 10.

BIT 4 (IW1)

BIT 3 (IW0)

INPUT RESOLUTION

0

0

16-bit data word

0

1

20-bit data word

1

0

24-bit data word

1

1

18-bit data word

Table 10 Input Data Resolution

DAC OUTPUT CONTROL

Bits 5, 6, 7 and 8 (PL[3:0]) of register M2 are used to control the output format as shown in Table 11.

PL3

PL2

PL1

PL0

LEFT OUTPUT

RIGHT OUTPUT

NOTE

0

0

0

0

MUTE

MUTE

Mute both channels

0

001

L

MUTE

0

010

R

MUTE

0

011

(L + R)/2

MUTE

0

100

MUTE

L

0

101

L

L

0

1

1

0

R

L

Reverse channels

0

111

(L + R)/2

L

1

000

MUTE

R

1

0

0

1

L

R

Stereo mode

1

010

R

R

1

011

(L + R)/2

R

1

100

MUTE

(L + R)/2

1

101

L

(L + R)/2

1

110

R

(L + R)/2

1

1

1

1

(L + R)/2

(L + R)/2

Mono mode

Table 11 Programmable Output Format