AK4646_11 Datasheet, PDF (45/81 Pages) Asahi Kasei Microsystems – Stereo CODEC with MIC/SPK-AMP

[AK4646]
■ De-emphasis Filter
The AK4646 includes the digital de-emphasis filter (tc = 50/15μs) which corresponds 3 kinds frequency (32kHz, 44kHz,
48kHz) by IIR filter. Setting the DEM1-0 bits enables the de-emphasis filter (Table 37).
DEM1
0
0
1
1
DEM0
Mode
0
44.1kHz
1
OFF
0
48kHz
1
32kHz
Table 37. De-emphasis Control
(default)
■ 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
0dB
A tte n u a tio n
256/fs
(1)
256/fs
(3)
-∞
GD
GD
(2)
Analog O utput
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.
MS0557-E-05
- 45 -
2011/01