WM8726
Production Data
HARDWARE CONTROL MODES
The WM8726 is hardware programmable providing the user with options to select input audio data
format, de-emphasis and mute.
MUTE AND AUTO MUTE OPERATION
Pin 10 (MUTE) controls selection of MUTE directly, and can be used to enable and disable the
automute function, or as an output of the automuted signal.
MUTEB PIN
DESCRIPTION
0
1
Normal Operation, MUTE off
Mute DAC channels
Floating
Enable IZD, MUTE becomes an output to indicate when IZD occurs.
Table 2 Mute and Automute Control
1.5
1
0.5
0
-0.5
-1
-1.5
-2
-2.5
0
0.001
0.002
0.003
0.004
0.005
0.006
Time(s)
Figure 7 Application and Release of MUTE
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. Refer to Figure 7.
The Infinite Zero Detect (IZD) 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 connected through a 10kohm 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. 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 source impedance) so can be used to drive
external mute circuits. AUTOMUTED will be removed as soon as any channel receives a non-zero
input.
PD Rev 4.1 September 2005
13
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
