ASAHI KASEI
[AK4370]
■ Digital Attenuator
The AK4370 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 7). At
DATTC bit = “1”, ATTL7-0 bits control both channel’s attenuation levels. At DATTC bit = “0”, ATTL7-0 bits control
the left channel level and ATTR7-0 bits control the right channel level.
ATTL7-0
Attenuation
ATTR7-0
FFH
FEH
FDH
FCH
:
0dB
−0.5dB
−1.0dB
−1.5dB
:
:
:
02H
01H
00H
−126.5dB
−127.0dB
MUTE (−∞)
Default
Table 7. 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 8). When the
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. The 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 8. Transition time between set values of ATT7-0 bits
MS0595-E-00
2007/03
- 21 -
AKM [ ASAHI KASEI MICROSYSTEMS ]
