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WM8569

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PP Rev 1.1 December 2005

15

The MUTE pin is an input to select mute or not mute. MUTE is active high; taking the pin high

causes the filters to soft mute, ramping down the audio signal over a few milliseconds. Taking MUTE

low again allows data into the filter.

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’d through a 10kΩ 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 (10kΩ 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.

IZD (Register Bit)

AUTOMUTED

(Internal Signal)

10k

Ω

Ω

Ω

Ω

MUTE (Register Bit)

SOFTMUTE

(Internal

Signal)

MUTE

PIN

Figure 8 Control of MUTE Modes

INPUT FORMAT SELECTION

In hardware mode, CSB/IDF and SCLK/IWL become input controls for selection of input data format

type and input data word length for both the ADC and DAC.

CSB/IDF

SCLK/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

(ADCLRC and DACLRC) are high for a minimum of 24 bit clocks (ADCBCLK and DACBCLK) and

low for a minimum of 24 bit clocks.

DE-EMPHASIS CONTROL

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

to be applied.

SDIN/DM

DE-EMPHASIS

0

Off

1

On

Table 8 De-emphasis Control