AK4367 Datasheet, PDF (16/38 Pages) Asahi Kasei Microsystems – OUTPUT MIXER & HP - AMP 24 BIT 2 CH DAC

ASAHI KASEI
[AK4367]
„ Digital Attenuator
The AK4367 has a channel-independent digital attenuator (256 levels, 0.5dB step). This digital attenuator is placed before
the D/A converter. ATTL/R7-0 bits set the attenuation level (0dB to −127dB or MUTE) for each channel (Table 4). At
DATTC bit = “1”, ATTL7-0 bits control both Lch and Rch attenuation levels. At DATTC bit = “0”, ATTL7-0 bits control
the Lch level and ATTR7-0 bits control the Rch level. When HPM bit = “1”, (L+R)/2 summation is done after volume
control.
ATTL7-0
ATTR7-0
Attenuation
FFH
0dB
FEH
−0.5dB
FDH
−1.0dB
FCH
−1.5dB
:
:
:
:
02H
−126.5dB
01H
−127.0dB
00H
MUTE (−∞) Default
Table 4. Digital Volume ATT values
The ATS bit sets the transition time between set values of ATT7-0 bits as either 1061/fs or 7424/fs (Table 5). When ATS
bit = “0”, a soft transition between the set values occurs(1062 levels). It takes 1061/fs (24ms@fs=44.1kHz) from
FFH(0dB) to 00H(MUTE). The ATTs are 00H when the PMDAC bit is “0”. When the PMDAC returns to “1”, the ATTs
fade to their current value. Digital attenuator is independent of the soft mute function.
ATS
ATT speed
0dB to MUTE
1 step
0
1061/fs
4/fs
Default
1
7424/fs
29/fs
Table 5. Transition time between set values of ATT7-0 bits
MOUT volume is controlled by ATTM3-0 bits when MMUTE bit = “0” (Table 6). Pop noise occurs when ATT3-0 bits
are changed.
MMUTE
ATTM3-0
Attenuation
0FH
0dB
0EH
−2dB
0DH
−4dB
0
0CH
−6dB
:
:
:
:
01H
−28dB
00H
−30dB
1
x
MUTE
Table 6. MOUT Volume ATT values
Default
MS0247-E-01
- 16 -
2004/11