ASAHI KASEI
[AK4112A]
n De-emphasis Filter Control
The AK4112A includes the digital de-emphasis filter (tc=50/15µs) by IIR filter corresponding to four sampling
frequencies (32kHz, 44.1kHz, 48kHz and 96kHz). When DEAU bit=“1”, the de-emphasis filter is enabled automatically
by sampling frequency and pre-emphasis information in the channel status. The AK4112A goes this mode at default.
Therefore, in Parallel Mode, the AK4112A is always placed in this mode and the de-emphasis filter is controlled by the
status bits in channel 1. In Serial Mode, DEM0/1 and DFS bits can control the de-emphasis filter when DEAU is “0”.
The internal de-empahsis filter is bypassed and the recovered data is output without any change if either pre-emphasis or
de-emphasis Mode is OFF.
FS96
FS1
FS0
Mode
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
44.1kHz
OFF
48kHz
32kHz
OFF
OFF
96kHz
OFF
Table 7. De-emphasis Auto Control at DEAU=“1” and PEM=“1”
DFS
DEM1
DEM0
Mode
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
44.1kHz
OFF
Default
48kHz
32kHz
OFF
OFF
96kHz
OFF
Table 8. De-emphasis Manual Control at DEAU=“0” and PEM=“1”
MS0020-E-00
2000/3
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AKM [ ASAHI KASEI MICROSYSTEMS ]
