AK4492ECB Datasheet, PDF (62/101 Pages) Asahi Kasei Microsystems – Quality Oriented 32-Bit 2ch DAC

[AK4492]
■ De-emphasis Filter (PCM Mode)
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 30. De-emphasis Control
DEM1 DEM0 Mode
0
0
44.1 kHz
0
1
OFF (default)
1
0
48 kHz
1
1
32 kHz
■ Output Volume (PCM Mode, DSD Mode, EXDF Mode)
The AK4492 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 31. Attenuation level of Digital Attenuator
ATTL/R[7:0]bits
(register 03-04H)
Attenuation Level
FFH
+0 dB
(default)
FEH
-0.5 dB
FDH
-1.0 dB
:
:
02H
-126.5 dB
01H
-127.0 dB
00H
MUTE (-∞)
The transition time of digital output volume is set by ATS[1:0] bits (Table 32). 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 32. 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.
016011073-E-00
- 62 -
2016/12