ASAHI KASEI
[AK4115]
The pre-emphasis information is detected and reported on PEM bit. This informations is extracted from channel 1 by
default. It can be switched to channel 2 by the CS12 bit in control register.
Byte 0
Bits 3-5
PEM
Pre-emphasis
0
1
OFF
ON
≠ 0X100
0X100
Table 15. PEM in Consumer Mode
Byte 0
Bits 2-4
PEM
Pre-emphasis
0
1
OFF
ON
≠110
110
Table 16. PEM in Professional Mode
De-emphasis Filter Control
The AK4115 includes a digital de-emphasis filter (tc=50/15µs). This is an IIR filter corresponds to four sampling
frequencies (32kHz, 44.1kHz and 48kHz). When DEAU bit=“1”, the de-emphasis filter is enabled automatically by the
sampling frequency and pre-emphasis information in the channel status. The AK4115 is in this mode by default. In
parallel control mode, the AK4115 is always placed in this mode and the status bits in channel 1 control the de-emphasis
filter. In serial control mode, DEM0/1 bits control the de-emphasis filter when the DEAU bit is “0”. The internal
de-emphasis filter is bypassed and the recovered data is available without any change if either the pre-emphasis or
de-emphasis mode is OFF. When the PEM bit is “0”, the internal de-emphasis filter is always bypassed.
PEM
FS3
0
0
FS2
0
0
FS1
0
1
FS0
0
0
Mode
44.1kHz
48kHz
32kHz
OFF
1
1
1
1
0
0
0
1
1
(Others)
x
x
x
x
OFF
Table 17. De-emphasis Auto Control at DEAU bit = “1” (Default)
PEM
DEM1
DEM0
Mode
44.1kHz
OFF
48kHz
32kHz
OFF
1
1
1
1
0
0
0
1
1
x
0
1
0
1
x
Default
Table 18. De-emphasis Manual Control at DEAU bit = “0”
MS0573-E-00
2006/12
- 27 -
AKM [ ASAHI KASEI MICROSYSTEMS ]
