[AK4492]
■ Digital Filter
Six types of digital filter in PCM mode and two types of digital filter in DSD mode are available in the
AK4492 for sound color selection of music playback.
In PCM mode, digital filter can be selected by the SD, SLOW and SSLOW pins if the AK4492 is in pin
control mode, and digital filter can be selected by SD, SLOW and SSLOW bits in register control mode
(Table 28).
Table 28. Digital Filter Setting
SSLOW
SD
0
0
1
1
0
0
1
1
SLOW
Mode
Sharp roll-off filter
Slow roll-off filter
0
0
0
0
1
1
1
1
0
1
0
1
0
1
0
Short delay sharp roll-off filter
Short delay slow roll-off filter
Super slow roll-off filter
Super slow roll-off filter
Low dispersion Shot delay filter)
N/A
(default)
1
Note 51. Do not use Reserved mode (SSLOW bit= “1”, SD bit= “1”, SLOW bit= “1”) in PCM mode.
In DSD mode, the cutoff frequency of digital filter can be switched by DSDF bit. Table 29 shows the cutoff
frequency of fs = 44.1 kHz. The cutoff frequency tracks the sampling frequency (fs). Do not set GC[2:0]
bits to “100” when DSDD bit = “0” and DSDF bit = “1”. Otherwise a pop noise may occur.
Table 29. DSD Filter Select
Cut Off Frequency
@fs=44.1kHz,
DSDF bit
DSD64fs DSD128fs DSD256fs
0
1
39 kHz
76 kHz
78 kHz
152 kHz
156 kHz (default)
304 kHz
016011073-E-00
2016/12
- 61 -
AKM [ ASAHI KASEI MICROSYSTEMS ]
