[AK4493]
017012230-E-00
2017/12
- 60 -
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DSD Signal Full-Scale (FS) Detection
The AK4493 has independent full-scale detection function for each channel in DSD mode.
Mute function of analog output signal becomes enabled after detecting full-scale signal by setting DDM bit
=
shows a block diagram of DSD signal playback. Input data of each channel pin (DSDL or
DSDR) is received via the DSD_IF block and full-scale detection is executed at the DSD full-scale
detection block. The AK4493 mutes the analog output when either L or R channel full-scale signal
becomes
“1” when DDM bit = “1”. To prevent click noise, DSD_IF block output signal is delayed for
“DDMT[1:0] bits s 8DCLK cycles” by register block until the signal is muted completely, thus the
analog output also delays.
If the input data of either Lch or Rch is continuously
“H” or “L” for the time set by DDMT[1:0] bits, the
AK4493 is in full-scale detection state (
) and corresponding DML or DMR bit becomes
“1”
independently. These bits only indicate
“1” while full-scale data is input. DML/DMR bit is “0” if the input
data is not full-scale in PCM/EXDF mode. Full-scale detection signal can also be output from the DZFL or
DZFR pin by setting DDMOE bit =
“1”. Refer to
for details. The AK4493 mutes the analog output
when full-scale data is input to either L or R channel. This analog output mute transition is depending on
the setting of DSDD bit that selects DSD playback path (
When DSDD bit =
“1” (Volume Bypass), the output data of DSD filter is changed to Zero data if the
AK4493 is in full-scale state. When DSDD bit =
“0” (Normal Path), the output data of DSD filter is changed
to Zero data and the data is soft muted by DATT block if the AK4493 is in full-scale state. Mute transition
time is set by ATS[1:0] bits from 255/2fs to 4080/2fs (fs = 30~48kHz in DSD mode). However, output
signal is muted to zero immediately after the AK4493 becomes full-scale detection state since it is much
depending on the DSD filter output data transition time.
Full-scale detection state is released when the input data of the full-scale input channel is toggled. The
operation after full-scale detection is released is according to DSDD bit setting that selects DSD playback
path (
).
If DSDD bit =
“1” (Volume Bypass), the AK4493 returns to normal operation as DSD filter output signal is
output and the output data is changed immediately when the full-scale detection state is released.
If DSDD bit =
“0” (Normal Path), the AK4493 returns to normal operation as DSD filter output signal is
output and the soft mute by the DATT block is released. The transition time until the output data returns to
normal after releasing full-scale detection state is according to the setting of ATS[1:0] bits since it is much
depending on the transition time of attenuating coefficient of DATT block.
Figure 48. DSD Block Diagram
