ASAHI KASEI
[AK4122]
De-emphasis Filter Control
The AK4122 includes the digital de-emphasis filter (tc=50/15µs) by IIR filter corresponding to three sampling
frequencies (32kHz, 44.1kHz and 48kHz).
(1) When input port is DIR
When the input port is DIR and DEAU bit = “1”, the de-emphasis filter is enabled automatically by sampling frequency
(FS3-0 bit) and pre-emphasis information in the channel status. DEM1-0 bits can control the de-emphasis filter when
DEAU bit = “0”. When the de-emphasis filter is OFF, the internal de-emphasis filter is bypassed. When PEM bit = “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 11. De-emphasis Auto Control (DEAU bit = “1”)
PEM
DEM1
DEM0
Mode
44.1kHz
OFF
48kHz
32kHz
1
1
1
1
0
0
1
1
0
1
0
1
Default
Table 12. De-emphasis Manual Control (DEAU bit = “0”)
(2) When input port is PORT1 or PORT2
When PORT1 or PORT2 is selected as input port, DEM1-0 bits can control the de-emphasis filter even if DEAU bit = “0”
or DEAU bit = “1”. In this case, the de-emphasis filter cannot enable automatically. When the de-emphasis filter is OFF,
the internal de-emphasis filter is bypassed.
DEM1
DEM0
Mode
44.1kHz
OFF
48kHz
32kHz
0
0
1
1
0
1
0
1
Default
Table 13. De-emphasis Manual Control
System Reset and Power-Down
The AK4122 has a full power-down mode for all circuits that is activated by the PDN pin, and a partial power-down mode
activated by the PWN bit. The AK4122 should be reset once at power-up by bringing PDN pin = “L”.
PDN pin:
All analog and digital circuits are placed in power-down and reset modes by bringing PDN pin = “L”. All the
registers are initialized and clocks are stopped. Read/Write operations to the registers are disabled.
PWN bit (Address 00H; D0):
Unlike the PDN pin operation described above, internal registers and mode settings are not initialized. Read/Write
operations to the registers are enabled.
MS0267-E-02
2004/07
- 23 -
AKM [ ASAHI KASEI MICROSYSTEMS ]
