WM8772_05 datasheet(22/73 Pages) WOLFSON

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WM8772EDS – 28 LEAD SSOP

Production Data

PD Rev 4.2 October 2005

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’ed 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 Figure 20.

IZD (Register Bit)

AUTOMUTED

(Internal Signal)

10k

Ω

MUTE (Register Bit)

SOFTMUTE

(Internal

Signal)

MUTE

Figure 20 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 both the ADC and DAC.

ML/I2S

MC/IWL

INPUT DATA MODE

24-bit right justified

20-bit right justified

16-bit I

24-bit I

Table 8 Input Format Selection

Note:

In 24 bit I

2S mode, any width of 24 bits or less is supported provided that the left/right clocks (LRC)

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

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

Off

Table 9 De-emphasis Control

WM8772 Datasheet(PDF) 22 Page - Wolfson Microelectronics plc

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