AK4456 Datasheet, PDF (45/84 Pages) Asahi Kasei Microsystems – 115dB 768kHz Advanced 32-bit DAC

[AK4456]
■ Output Volume (PCM mode, DSD mode)
The AK4456 has a channel-independent digital attenuator (256 levels, 0.5dB steps). Attenuation level of each
DAC1-3 can be set by ATT7-0 bits (register 0A-11H), respectively (Table 17). Input data is attenuated from
0dB to -127dB including Mute. The transition between set values is a soft transition, thus no switching noise is
occurred.
ATT7-0bits
(register 0A-11H)
Attenuation Level
FFH
+0dB
(default)
FEH
-0.5dB
FDH
-1.0dB
:
:
:
:
02H
-126.5dB
01H
-127.0dB
00H
MUTE (-∞)
Table 17. Attenuation level of Digital Attenuator
Transition time between set values of ATL/R7-0 bits can be selected by the ATS1-0 bits (Table 18). The
transition between set values is a soft transition in Mode0/1/2/3 eliminating switching noise in the transition.
The register settings are maintained when switching the mode between PCM and DSD modes.
Mode
ATS1
ATS0 ATT speed
0
0
0
4080/fs ^(default)
1
0
1
2040/fs
2
1
0
510/fs
3
1
1
255/fs
Table 18. Transition Time between Set Values of ATT7-0 bits
The transition between set values is a soft transition of 4080 levels in mode 0. It takes 4080/fs (92.5ms
@fs=44.1kHz) 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.
In DSD mode, the digital volume is set to MUTE by setting ATT7-0 bits = “02H” or “01H”.
015006886-E-00
- 45 -
2015/06