WM8768 Wolfson Microelectronics plc, WM8768 Datasheet - Page 27

• Manufacturer Part Number: WM8768
• Description: 24-bit, 192khz 8-channel Dac
• Manufacturer: Wolfson Microelectronics plc

Production Data
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AUTOMUTE
The WM8768 can automute by counting zero samples on the DIN1/2/3/4 inputs. When 1024 zero
samples are counted on one channel, one of four internal zero flags (zflag1/2/3/4 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, zflag1/2/3/4 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 10kOhms
Table 12 Effect of DZFM on Mute Pin Output
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 WM8768 drives the Mute pin high, the output DACs will
also softmute as described by Table 13.
Table 13 Mute Pin Decode when Mute Pin as Output
{DZFM4,DZFM
MPD
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
[1:0]}
000
001
010
011
100
101
110
111
{DZFM4,DZFM [1:0]}
CONDITION UNDER WHICH MUTE
000
001
010
011
100
101
110
111
000
001
010
011
100
101
110
111
Zflag1, 2, 3 and 4 all high
Zflag1, 2 and 3 high
Zflag1 and 2 high
Zflag3 and 4 high
PIN DRIVEN HIGH
Zflag1 high
Zflag2 high
Zflag3 high
Zflag4 high
CHANNELS MUTED WHEN
MUTE PIN DRIVEN HIGH
CH1, CH2 and CH3
CH1 and CH2
CH3 and CH4
All Channels
All Channels
All Channels
All Channels
All Channels
All Channels
All Channels
All Channels
All Channels
CH1
CH2
CH3
CH4
PD Rev 4.2 July 2005
WM8768
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