wm8742 Wolfson Microelectronics plc, wm8742 Datasheet - Page 41

• Manufacturer Part Number: wm8742
• Description: 24-bit 192khz Dac With Advanced Digital Filtering
• Manufacturer: Wolfson Microelectronics plc

Production Data
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ZERO FLAG
In hardware control mode the ZFLAG pin asserts when 1024 consecutive zero samples are applied to
the left and right channels of the WM8742 when in PCM mode. In DSD mode, the ZFLAG has no
function.
In hardware mode there is no access to the infinite zero detect and so there is no automute function.
If this functionality is required, software mode must be used. Figure 27 shows the MUTEB and
ZFLAG configuration.
Figure 27 Hardware Control Mode MUTEB and ZFLAG Configuration
DE-EMPHASIS CONTROL AND ANTI-CLIPPING MODE
In hardware control mode, de-emphasis is supported with a maximum error of +1.5dB at a sampling
rate of 44.1kHz.
Audio material is regularly recorded up to 0dB level and heavily compressed. This causes clipping
and distortion when the digital media is applied to a DAC. In order to prevent this in the WM8742, an
anti-clipping mode is provided, which attenuates the digital signal by 2dB as it is processed through
the digital filters.
Under hardware control de-emphasis and the anti-clipping mode are only available when using PCM
mode.
Table 49 DEEMPH Hardware Control Pin Function
PIN
26
DEEMPH
NAME
SDIN/
Deemphasis Control
0 = De-emphasis off
1 = De-emphasis on
Z = Digital filter anti-clipping mode
DESCRIPTION
PD, Rev 4.2, August 2009
WM8742
41