Production Data
WM8522
AUTOMUTE
The WM8522 can automute by counting zero samples on the DIN1/2/3 inputs. When 1024 zero
samples are counted on one channel, one of three internal zero flags (zflag1/2/3 shown in figure 2) is
raised. Depending on the external hardware and settings of DZFM, MPD and IZD, different automute
operations are possible.
MUTE PIN AS OUTPUT
If the MUTE pin is connected to a high impedance (input to external mute circuitry for example) or left
floating, zflag1/2/3 will be output on the Mute pin dependent on DZFM settings. This is described in
Table 12 below. The output impedance of the MUTE pin is 10kΩ.
DZFM [1:0]
CONDITION UNDER WHICH
MUTE PIN DRIVEN HIGH
00
01
10
11
Zflag1/2/3 all high
Zflag1 high
Zflag2 high
Zflag3 high
Table 12 Effect of DZFM on Mute Pin Decode
When the Mute pin is used as an output, its logic level remains connected to the DZFM selector
inside the chip (see figure 1). So, when the WM8522 drives the Mute pin high, the output DACs will
also softmute as described by Table 13.
MPD
DZFM [1:0]
CHANNELS MUTED WHEN
MUTE PIN DRIVEN HIGH
0
0
0
0
1
1
1
1
00
01
10
11
00
01
10
11
All Channels
CH1
CH2
CH3
All Channels
All Channels
All Channels
All Channels
Table 13 Mute Pin Decode when Mute Pin as Output
INFINITE ZERO DETECT
When it is set, the IZD register causes an analogue mute of the DAC channel output amplifier both
when there are 1024 zeros on that channel’s DIN pin or when it is manually muted by DMUTE or
MUTEALL.
REGISTER ADDRESS
0000010
BIT
LABEL
DEFAULT
DESCRIPTION
IZD Enable
4
IZD
0
DAC Channel Control
0 : Disable infinite zero mute
1: Enable infinite zero mute
This operation is only available in software mode and can sometimes create a very small click at the
output of the device.
PD Rev 4.0 July 2006
25
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
