ASAHI KASEI
[AKD4385-SC]
<KM082701> 4 2006/04
SW1 setting
[SW1](PDN): Reset of AK4385. Select “H” during operation
.
External Analog Filter Circuit
The 2nd order LPF (fc=93.2kHz, Q=0.712) which adds differential outputs of the AK4385 is implemented on the board. When
the further attenuation of the out-of-band noise is needed, some additional LPF is required. Analog signal is output through
BNC connectors on the board. And the output level of the AK4382A is 5.5Vpp@5V.
LOUT-
(ROUT-)
-
LOUT+
(ROUT+)
+15V
-15V
NJM4580D
R
1
C
1
R
3
R
2
C
2
R
1
R
3
R
2
C
2
22u
10k
+
100
Figure 4. On-board analog filter
R
1
R
2
R
3
C
1
C
2
4.7k 4.7k 200 3300p
470p
Table 4. The value of R, C on this board
fin 20kHz
40kHz
80kHz
Frequency Response
-0.003dB
-0.122dB
-1.821dB
Table 5. Frequency Response of LPF
<Calculation>
fc=
ω
0
2
π
,
ω
0
=
1
2C
1
C
2
R
2
R
3
,
Q=
2C
1
ω
0
.
+
1
R
1
+
1
R
2
1
R
3
Amplitude = 20 log
[1-(f/fc)
2
]
2
+[(1/Q)(f/fc)]
2
K
[dB],
K=
R
2
R
1
,
