[AK4438]
■ Digital Filter
Five digital filters are available for playback, providing a choice of different sound colors. These digital
filters are selected by SD bit, SLOW bit and SSLOW bit.
SSLOW
SD bit
SLOW bit
Mode
0
0
0
0
1
0
0
1
1
*
0
1
0
1
*
Sharp roll-off filter
Slow roll-off filter
Short delay Sharp roll-off filter
Short delay Slow roll-off filter
Super Slow Roll-off Mode
(default)
Table 11. Digital Filter Setting (*: don’t care)
■ Zero Detection
The AK4438 has channel-independent zero detection function. Zero detection channels (AOUTL1-4 and
AOUTR1-4 pins) can be selected by 07H/08H registers (L1-4 bits, R1-4 bits). When the input data at each
channel is continuously zeros for 8192 LRCK cycles, the DZF pin goes to “H”. The DZF pin immediately
returns to “L” if the input data of each channel is not zero. If the RSTN bit is “0”, the DZF pins of both
channels go to “H”. The DZF pin of both channels go to “L” after 4 ~ 5/fs when RSTN bit returns to “1”. The
DZFB bit can invert the polarity of the DZF pin. If all channels are disabled, the DZF pin outputs “Not
zero”.
DZFB bit
0
Data
Not zero
Zero detect
Not zero
Zero detect
DZF pin
L
H
H
L
1
Not zero: One of the zero detection channels set by L1-4 bits and R1-4 bits does not detect zero.
Zero detect: All zero detection channels set by L1-4 bits and R1-4 bits detect zero.
Table 12. DZF Pin Function
016001925-E-00
2016/03
- 34 -
AKM [ ASAHI KASEI MICROSYSTEMS ]
