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| AKD4385 Datasheet, PDF (4/27 Pages) Asahi Kasei Microsystems – Evaluation board for AK4385 | |||
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ASAHI KASEI
[AKD4385-B]
< External Analog 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-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 AK4385 is 5.5Vpp@5V.
LOUT-
(ROUT-)
LOUT+
(ROUT+)
R1
C1
R1
R3
R3
R2
R2
C2
+15V
-
+
C2
22u
NJM4580D
-15V
100
10k
Figure 4. On-board analog filter
R1
R2
R3
C1
C2
4.7k
4.7k
200
3300p
470p
Table 4. The value of R, C on this board
fin
20kHz
40kHz
Frequency Response -0.003dB -0.122dB
Table 5. Frequency Response of LPF
80kHz
-1.821dB
<Calculation>
Amplitude = 20 log
K
[dB],
[1-(f/fc)2] 2+[(1/Q)(f/fc)] 2
K=
R2
R1
,
fc=
Ï0
2Ï
,
Ï0=
1
,
2C1C2R2R3
Q=
2C1Ï0
.
1
R1
+
1
R2
+
1
R3
<KM075400>
-4-
2004/07
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