ASAHI KASEI
[AK4522]
De-emphasis Filter
The DAC of AK4522 includes the digital de-emphasis filter (tc=50/15us) by IIR filter. This filter corresponds to three
frequencies (32kHz, 44.1kHz, 48kHz). The de-emphasis filter selected by DEM0 and DEM1 is enabled for input audio
data. The de-emphasis is also disabled at DEM0=”1” and DEM1=”0”.
DEM1
DEM0
Mode
44.1kHz
OFF
48kHz
32kHz
0
0
1
1
0
1
0
1
Table 3. De-emphasis filter control
Soft Mute Operation
Soft mute operation is performed at digital domain. When SMUTE goes to “H”, the output signal is attenuated by -∞
during 1024 LRCK cycles. When SMUTE is returned to “L”, the mute is cancelled and the output attenuation gradually
changes to 0dB during 1024 LRCK cycles. If the soft mute is cancelled within 1024 LRCK cycles after starting the
operation, the attenuation is discontinued and returned to 0dB. The soft mute is effective for changing the signal source
without stopping the signal transmission.
SMUTE
1024/fs
(1)
1024/fs
0dB
(3)
Attenuation
-∞
GD
(2)
GD
Noise level
-100dB
Notes:
(1) The output signal is attenuated by -∞ during 1024 LRCK cycles (1024/fs).
(2) Analog output corresponding to digital input has the group delay (GD).
(3) If the soft mute is cancelled within 1024 LRCK cycles, the attenuation is discontinued and returned to 0dB.
Figure 5. Soft Mute Operation
M0020-E-02
2012/01
- 11 -
AKM [ ASAHI KASEI MICROSYSTEMS ]
