AK4342 Datasheet, PDF (21/43 Pages) Asahi Kasei Microsystems – 24-Bit Stereo DAC with HP-AMP & 2V Line-Out

ASAHI KASEI
[AK4342]
„ Soft Mute
Soft mute operation is performed in the digital domain of the DAC input. When the SMUTE bit goes to “1”, the output
signal is attenuated by −∞ during ATT_DATA×ATT transition time (Figure 16) from the current ATT level. When
SMUTE bit is returned to “0”, the mute is cancelled and the output attenuation gradually changes to the ATT level during
ATT_DATA×ATT transition time. If the soft mute is cancelled before attenuating to −∞ after starting the operation, the
attenuation is discontinued and returned to ATT level by the same cycle. The soft mute is effective for changing the signal
source without stopping the signal transmission.
SMUTE bit
ATT Level
Attenuation
STS1-0 bits
(1)
STS1-0 bits
(1)
(3)
-∞
GD
GD
(2)
Analog Output
Figure 16. Soft Mute Function
Notes:
(1) ATT_DATA×ATT transition time. For example, this time is 510LRCK cycles at normal speed mode and STS1-0
bit = “01” and ATT_DATA = “128”.
(2) Analog output corresponding to digital input has group delay (GD).
(3) If the soft mute is cancelled before attenuating to −∞ after starting the operation, the attenuation is discontinued
and returned to ATT level by the same cycle.
„ De-emphasis Filter
The AK4342 includes a digital de-emphasis filter (tc = 50/15µs) via an IIR filter. This filter corresponds to three
frequencies (32kHz, 44.1kHz and 48kHz). This setting is done via control register (DEM1-0 bits). (See Table 8). When
the AK4342 is half speed mode or double speed mode, the DEM1-0 bits are ignored and the de-emphasis filter is disabled.
DEM1 bit
DEM0 bit De-emphasis
0
0
44.1kHz
0
1
OFF
1
0
48kHz
1
1
32kHz
Table 8. De-emphasis Filter Frequency control
Default
MS0506-E-02
- 21 -
2006/07