Preliminary Technical Data

WM8766

w

PTD Rev 2.3 February 2004

13

The automute function detects a series of ZERO value audio samples of 1024 samples long being

applied to both channels. After such an event, a latch is set whose output (AUTOMUTED) is wire

OR’ed through a 10k

Ω resistor to the MUTE pin. Thus if the MUTE pin is not being driven, the

automute function will assert mute.

If MUTE is tied low, AUTOMUTED is overridden and will not mute unless the IZD register bit is set. If

MUTE is driven from a bi-directional source, then both MUTE and automute functions are available. If

MUTE is not driven, AUTOMUTED appears as a weak output (10k

Ω source impedance) and can be

used to drive external mute circuits. AUTOMUTED will be removed as soon as any channel receives

a non-ZERO input.

A diagram showing how the various Mute modes interact is shown below Figure 8.

IZD (Register Bit)

AUTOMUTED

(Internal Signal)

10k

Ω

Ω

Ω

Ω

MUTE (Register Bit)

SOFTMUTE

(Internal

Signal)

MUTE

PIN

Figure 8 Selection Logic for MUTE Modes

INPUT FORMAT SELECTION

In hardware mode, ML/I2S and MC/IWL become input controls for selection of input data format type

and input data word length for the DAC.

ML/I2S

MC/IWL

INPUT DATA MODE

0

0

24-bit right justified

0

1

20-bit right justified

1

0

16-bit I

1

1

24-bit I

Table 7 Input Format Selection

Note:

In 24 bit I

(LRCLK) are high for a minimum of 24 bit clocks (BCLK) and low for a minimum of 24 bit clocks. If

exactly 32 bit clocks occur in one left/right clock (16 high, 16 low) the chip will auto detect and run a

16 bit data mode.

DE-EMPHASIS CONTROL

In hardware mode, the MD/DM pin becomes an input control for selection of de-emphasis filtering to

be applied.

MD/DM

DE-EMPHASIS

0

Off

1

On

Table 8 De-emphasis Control