ASAHI KASEI
[AK4122]
Sampling Frequency and Pre-emphasis Detection
The AK4122 has two methods for detecting the sampling frequency. The sampling frequency is detected by comparing
the recovered clock to the MCLK2 or OMCLK frequency, and the detected frequency is reported on FS3-0 bits. XTL1-0
bits, ICKS1-0 bits and OCKS1-0 bits can select reference MCLK2 and OMCLK (Table 16). When XTL1-0 bits = “11”,
the sampling frequency is detected by the channel status sampling frequency information. The detected frequency is
reported on FS3-0 bits. The default values of FS3-0 bits are “0001”. In case of detecting the sampling frequency by
MCLK when DIR is used, MCLK (MCLK2 or OMCLK) of selected output port (PORT2 or PORT3) should be input.
MCLK2 or OMCLK
XTL1
0
XTL0
0
MCLK Frequency
ICKS1 / OCKS1
ICKS0 / OCKS0
0
0
1
1
0
0
1
1
0
0
1
1
-
0
1
0
1
0
1
0
1
0
1
0
1
-
11.2896MHz
22.5792MHz
16.9344MHz
33.8688MHz
12.288MHz
24.576MHz
18.432MHz
36.864MHz
24.576MHz
N/A
0
1
1
1
0
1
36.864MHz
N/A
Use channel status
Default
Table 16. Reference MCLK Frequency
Except XTL1-0 bit = “11”
XTL1-0 bit = “11”
Consumer Mode
Register Output
Professional Mode
fs
Clock comparison
(Note 1)
(Note 2)
Byte3
Bit3,2,1,0
Byte0
Bit7,6
Byte4
Bit6,5,4,3
FS3 FS2 FS1 FS0
0
0
0
0
1
1
0
0
0
0
0
0
0
0
1
1
0
1
0
1
0
1
0
0
44.1kHz
Reserved
48kHz
32kHz
88.2kHz
96kHz
0000
0001
0010
0011
(1000)
(1010)
01
(others)
10
0000
0000
0000
0000
1010
0010
± 3%
-
± 3%
± 3%
± 3%
11
00
00
± 3%
Table 17. fs Information
Note 1. At least ±3% range is identified as the value in the Table 17. In case of an intermediate frequency of these two,
FS3-0 bits indicate the nearer value. When the frequency is much larger than 96kHz or much smaller than 32kHz,
FS3-0 bits may indicate “1100”, “1110” or “0001”.
Note 2. In consumer mode, Byte3 Bit3-0 are copied to FS3-0.
The pre-emphasis information is detected and reported on the PEM bit. This information is extracted from channel 1 by
default (CS12 bit = “0”). It can be switched to channel 2 by changing the CS12 bit in the control register.
Consumer mode
Byte0
Professional mode
Byte0
PEM bit Pre-emphasis
Bit3,4,5
Bit2,3,4
0
1
OFF
ON
≠ 0X100
0X100
≠ 100
100
Table 18. PEM Information
MS0267-E-02
2004/07
- 27 -
AKM [ ASAHI KASEI MICROSYSTEMS ]
