[AK4117]
■ Sampling Frequency and Pre-emphasis Detection
The AK4117 has two methods for detecting the sample frequency:
1) Clock comparison between recovered clock and the X’tal oscillator
FS3-0 bits indicate the detected RX input frequency referred to X’tal frequency. XTL1-0 bits select the reference
X’tal frequency (Table 4).
2) Sampling frequency information on channel status
When XTL1-0= “11”, FS3-0 bits indicate the decoded sampling frequency information from channel status.
XTL1
XTL0
X’tal Frequency
11.2896MHz
12.288MHz
24.576MHz
(Use channel status)
0
0
1
1
0
1
0
1
Default
Table 4. Reference X’tal frequency
Except XTL1-0= “11”
XTL1-0= “11”
Consumer
mode
(Note 11)
Byte3
Register output
fs
Professional mode
Clock comparison
(Note 10)
Byte0
Bit7,6
Byte4
Bit6,5,4,3
FS3
FS2
FS1
FS0
Bit3,2,1,0
0
0
0
0
1
1
1
1
0
0
0
0
0
0
1
1
44.1kHz
Reserved
48kHz
32kHz
88.2kHz
96kHz
0 0 0 0
0 0 0 1
0 0 1 0
0 1
0
0
1
1
0
1
0
1
0
1
0
1
0
0
0
0
0 0 0 0
(Others)
44.1kHz ± 3%
Reserved
1 0
1 1
0 0
0 0
0 0
0 0
0 0 0 0
0 0 0 0
1 0 1 0
0 0 1 0
1 0 1 1
0 0 1 1
48kHz ± 3%
32kHz ± 3%
88.2kHz ± 3%
96kHz ± 3%
176.4kHz ± 3%
192kHz ± 3%
0 0 1 1
( 1 0 0 0 )
( 1 0 1 0 )
( 1 1 0 0 )
( 1 1 1 0 )
176.4kHz
192kHz
Note 10. At least ±3% range is identified as the value in the Table 5. In case of an intermediate frequency of these two,
FS3-0 bits indicate the nearer value. When the frequency is much larger than 192kHz or much smaller than
32kHz, FS3-0 bits may indicate “0001”.
Note 11. In consumer mode, Byte3 Bit3-0 are copied to FS3-0.
Table 5. Sampling frequency information
The pre-emphasis information is detected and reported on the PEM bit. This information is extracted from channel 1 by
default (CS12=0). It can be switched to channel 2 by changing the CS12 bit in the control register.
Consumer mode
Professional mode
PEM
Pre-emphasis
Byte 0
Byte 0
Bits 3-5
Bits 2-4
0
1
OFF
ON
≠ 0X100
0X100
≠110
110
Table 6. Pre-emphasis information
MS0157-E-04
2010/08
- 13 -
AKM [ ASAHI KASEI MICROSYSTEMS ]
