Datasheet
[AK4646]
MS0557-E-06 2011/06
- 45 -
■ De-emphasis Filter
The AK4646 includes the digital de-emphasis filter (tc = 50/15
μs) which corresponds 3 kinds frequency (32kHz, 44kHz,
48kHz) by IIR filter. Setting the DEM1-0 bits enables the de-emphasis filter (
Table 37).
DEM1 DEM0 Mode
0 0 44.1kHz
0 1 OFF (default)
1 0 48kHz
1 1 32kHz
Table 37. De-emphasis Control
■ Soft Mute
Soft mute operation is performed in the digital input domain. When the SMUTE bit goes to “1”, the input signal is
attenuated by
−∞ (“0”) during the cycle of 256/fs (5.8msec@fs=44.1kHz). When the SMUTE bit is returned to “0”, the
mute is cancelled and the input attenuation gradually changes to 0dB during the cycle of 256/fs (5.8msec@fs=44.1kHz).
If the soft mute is cancelled within the cycle of 256/fs (5.8msec@fs=44.1kHz), the attenuation is discontinued and
returned to 0dB. The soft mute for Playback operation is effective for changing the signal source without stopping the
signal transmission.
SMUTE bit
A
ttenuation
256/fs
0dB
-
∞
256/fs
GD
GD
(1)
(2)
(3)
A
nalog Output
Figure 30. Soft Mute Function
(1)
The input signal is attenuated by −∞ (“0”) during the cycle of 256/fs (5.8msec@fs=44.1kHz).
(2)
Analog output corresponding to digital input has the group delay (GD).
(3)
If the soft mute is cancelled within the cycle of 256/fs (5.8msec@fs=44.1kHz), the attenuation is discounted and
returned to 0dB within the same cycle.