WM8766 Wolfson Microelectronics plc, WM8766 Datasheet - Page 25

• Manufacturer Part Number: WM8766
• Description: 24-bit, 192khz 6-channel Dac
• Manufacturer: Wolfson Microelectronics plc

Production Data
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AUTOMUTE
The WM8766 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 10kOhms
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 WM8766 drives the Mute pin high, the output DACs will
also softmute as described by Table 13.
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.
This operation is only available in software mode and can sometimes create a very small click at the
output of the device.
Table 13 Mute Pin Decode when Mute Pin as Output
REGISTER ADDRESS
DAC Channel Control
DZFM [1:0]
MPD
00
01
10
11
0
0
0
0
1
1
1
1
0000010
CONDITION UNDER WHICH
DZFM [1:0]
MUTE PIN DRIVEN HIGH
00
01
10
11
00
01
10
11
Zflag1/2/3 all high
Zflag1 high
Zflag2 high
Zflag3 high
BIT
4
CHANNELS MUTED WHEN
LABEL
MUTE PIN DRIVEN HIGH
IZD
All Channels
All Channels
All Channels
All Channels
All Channels
CH1
CH2
CH3
DEFAULT
0
IZD Enable
0 : Disable infinite zero mute
1: Enable infinite zero mute
DESCRIPTION
PD Rev 4.1 July 2005
WM8766
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