Product Preview
WM8741
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 WM8741 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 & ZFLAG Configuration
DE-EMPHASIS CONTROL AND ANTI-CLIPPING MODE
In hardware control mode, de-emphasis is supported at a sampling rate of 44.1kHz. De-emphasis is
supported at 32kHz and 48kHz sampling rates in software control mode.
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 WM8741, 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.
PIN
NAME
SDIN/
DESCRIPTION
Deemphasis Control
26
DEEMPH
0 = De-emphasis off
1 = 44.1kHz de-emphasis on
Z = Digital filter anti-clipping mode
Table 47 DEEMPH Hardware Control Pin Function
PP Rev 1.3 October 2007
41
w
WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
