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
Attenuation
ATTR7-0
FFH
FEH
FDH
FCH
:
0dB
−0.5dB
−1.0dB
−1.5dB
:
Default
:
:
02H
01H
00H
−126.5dB
−127.0dB
MUTE (−∞)
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.
ATT speed
ATS
0dB to MUTE
1061/fs
1 step
4/fs
29/fs
0
1
Default
7424/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
0dB
0FH
0EH
0DH
0CH
:
−2dB
−4dB
−6dB
:
0
1
:
:
01H
00H
x
−28dB
−30dB
MUTE
Default
Table 6. MOUT Volume ATT values
MS0247-E-02
2005/10
- 16 -
AKM [ ASAHI KASEI MICROSYSTEMS ]
