AK4497 Datasheet, PDF (58/98 Pages) Asahi Kasei Microsystems – Quality Oriented 32-Bit 2ch DAC

[AK4497]
■ De-emphasis Filter (PCM)
A digital de-emphasis filter is available for 32kHz, 44.1kHz or 48kHz sampling rates (tc = 50/15µs) and is
enabled or disabled by DEM1-0 pins or DEM1-0 bits. When DSD mode or EXDF mode, DEM1-0 bits are
ignored. The setting value is held even if PCM, DSD and EXDF mode is switched.
Table 29. De-emphasis Control
DEM1 DEM0 Mode
0
0
44.1kHz
0
1
OFF (default)
1
0
48kHz
1
1
32kHz
■ Output Volume (PCM, DSD, EXDF)
The AK4497 includes channel independent digital output volumes (ATTL/R) with 256 levels at 0.5dB step
including MUTE. When changing output levels, it is executed in soft transition thus no switching noise
occurs during these transitions. It can attenuate the input data from 0dB to -127dB and mute when
assuming the output signal level is 0dB when ATTL/R[7:0] bits = FFH.
Table 30. Attenuation level of Digital Attenuator
ATTL/R[7:0]bits
(register 03-04H)
Attenuation Level
FFH
+0dB
(default)
FEH
-0.5dB
FDH
-1.0dB
:
:
:
:
02H
-126.5dB
01H
-127.0dB
00H
MUTE (-∞)
The transition time of digital output volume is set by ATS[1:0] bits (Table 31). When changing output
levels between Mode0-3, it is executed in soft transition thus no switching noise occurs during these
transitions. Register setting values will be kept even switching the PCM and DSD modes.
Mode
0
1
2
3
Table 31. Transition Time between Set Values of ATT[7:0] bits
ATS1 ATS0
ATT speed
EXDF bit=”0”,
EXDF bit=”1”
DP bit=”1”
DP bit=”0”
DP bit=”0”
0
0
4080/fs
4080*WCK Cycle
4080/(2*fs)
0
1
2040/fs
2040*WCK Cycle
2040/(2*fs)
1
0
510/fs
510*WCK Cycle
510/(2*fs)
1
1
255/fs
255*WCK Cycle
255/(2*fs)
(default)
It takes 4080/fs (92.5ms@fs=44.1kHz) from FFH (0dB) to 00H (MUTE) in Mode 0. The attenuation level is
initialized to FFH (0dB) by setting the PDN pin = “L”.
If the volume is changed during reset period, the output volume will become a setting value after releasing
the reset. It will change to a setting value immediately if the volume is changed within 5/fs after releasing
reset.
Rev. 0.1
- 58 -
2015/11