AK4117_10 Datasheet, PDF (13/37 Pages) Asahi Kasei Microsystems – Low Power 192kHz Digital Audio Receiver

[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
0
0
1
1
XTL0
0
1
0
1
X’tal Frequency
11.2896MHz
12.288MHz
24.576MHz
(Use channel status)
Default
Table 4. Reference X’tal frequency
Except XTL1-0= “11”
XTL1-0= “11”
Register output
fs
FS3 FS2 FS1 FS0
Clock comparison
(Note 10)
Consumer
mode
(Note 11)
Byte3
Bit3,2,1,0
Professional mode
Byte0
Bit7,6
Byte4
Bit6,5,4,3
0
0
0
0
44.1kHz
44.1kHz ± 3%
0000
01
0000
0
0
0
1 Reserved
Reserved
0001
(Others)
0
0
1
0
48kHz
48kHz ± 3%
0010
10
0000
0
0
1
1
32kHz
32kHz ± 3%
0011
11
0000
1
0
0
0
88.2kHz
88.2kHz ± 3%
(1000)
00
1010
1
0
1
0
96kHz
96kHz ± 3%
(1010)
00
0010
1
1
0
0 176.4kHz
176.4kHz ± 3%
(1100)
00
1011
1
1
1
0
192kHz
192kHz ± 3%
(1110)
00
0011
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.
PEM Pre-emphasis
0
OFF
1
ON
Consumer mode
Byte 0
Bits 3-5
≠ 0X100
0X100
Professional mode
Byte 0
Bits 2-4
≠110
110
Table 6. Pre-emphasis information
MS0157-E-04
- 13 -
2010/08