[AK4438]
■ Digital Volume Function
The AK4438 has a channel-independent digital attenuator (256 levels, 0.5dB steps). Attenuation level of
each DAC1-4 can be set by ATT7-0 bits (register 0A-11H), respectively (Table 13).
ATT7-0bits
Attenuation Level
(register 0A-11H)
FFH
FEH
FDH
:
+0dB
-0.5dB
-1.0dB
:
(default)
:
:
02H
01H
00H
-126.5dB
-127.0dB
MUTE (-∞)
Table 13. Attenuation level of Digital Attenuator
Transition time between set values of ATT7-0 bits can be selected by the ATS1-0 bits (Table 14). The
transition between set values is a soft transition in Mode0/1/2 eliminating switching noise in the transition.
Mode
ATS1
ATS0
ATT speed
4080/fs
2040/fs
510/fs
0
1
2
3
0
0
1
1
0
1
0
1
(default)
255/fs
Table 14. Transition Time of Digital Volume
The transition between set values is a soft transition of 4080 levels in Mode 0. It takes 4080/fs (85ms
@fs=48kHz) from FFH to 00H. If the PDN pin goes to “L”, ATT7-0 bits are initialized to FFH.
If the digital volume is changed during reset, the volume will be changed to the setting value after
releasing the reset. If the volume is changed in 5/fs after releasing a reset, the volume is changed
immediately without soft transition.
016001925-E-00
2016/03
- 35 -
AKM [ ASAHI KASEI MICROSYSTEMS ]
