ASAHI KASEI
[AK4121]
Soft Mute Operation
When the SMUTE pin goes to “H”, the output signal is attenuated from 0dB to −∞dB during 1024 OLRCK cycles.
When the SMUTE pin returns to “0”, the mute is cancelled and the attenuation gradually changes to 0dB during 1024
OLRCK cycles. If the soft mute is cancelled before attenuating to −∞, the attenuation is discontinued and returns to 0dB.
This return takes the same number of clock cycles as the point at which the soft mute cancel was initiated, i.e. if 500
clock cycles passed and then a soft mute cancel was issued, it will take 500 clock cycles to return to 0dB. The soft mute
is used primarily when changing the signal source.
SMUTE
0dB
Attenuation Level
at SDTO
-
dB
∞
(2)
(1)
(1)
Notes:
(1) Transition time. 1024 OLRCK cycles (1024/fso).
(2) If the soft mute is cancelled before attenuating to −∞ after starting the operation, the attenuation is discontinued
and returned to 0dB by the same number of clock cycles.
Figure 4. Soft Mute
De-emphasis Filter
A digital de-emphasis filter is available for 32, 44.1 or 48kHz sampling rates (tc=50/15µs) and is enabled or disabled
with DEM0 and DEM1.
DEM1
DEM0
Mode
0
0
1
1
0
1
0
1
44.1kHz
OFF
Default
48kHz
32kHz
Table 4. De-emphasis Filter Control
MS0191-E-03
2004/08
- 11 -
AKM [ ASAHI KASEI MICROSYSTEMS ]
