M61512FP Datasheet, PDF (11/13 Pages) Mitsubishi Electric Semiconductor – 5.1ch Electronic Volume

MITSUBISHI SOUND PROCESSORS
M61512FP
5.1ch Electronic Volume
(5)Equivalent circuit of Bass Boost
INPUT
+
OUTPUT
SEL
-
200
The circuit for decrease in
switching noise
Go
0dB
Q=4(G=10dB)
The circuit figure of positive feedback two order high pass
filter circuit on bass boost part.
R1
VIN
C1
C2
+K
R2
fo
RL=70KΩ OVER(Notice)
VOUT
The amplitude characteristics of two
order high pass filter circuit (Reference)
Q
G0
1
0~1dB
2
6dB
4
10dB
5
13dB
10
20dB
The transmission function is
VOUT
=
VIN
s² + s
Ks²
1
1
1
1
+
+(1-K)
+
R2C1 R2C2
R1C1 R1R2C1C2
1
ωo² = _R1R2C1C2
1
Q=
R1C1 R1C2
R2C2
+
+(1-K)
R2C2 R2C1
R1C1
The bass boost part is consist of two order high pass filter circuit.
We show an example how to calculate design value of bass boost part.
We let C1=C2 are Cf and K is +1.
Above equation is shown below.
Rf=1/(0Cf) • • • (1)
R1=Rf/2Q • • • (2)
R2=2QRf • • • (3)
We let ω is 2π×70Hz and Q is 10 in the case of the cutoff
frequency is 70Hz and Q is 10.
We let C1=C2=Cf are 0.1µF.
From equation(1),(2),(3)
Rf=23.5KΩ
R1=1.18KΩ
R2=470KΩ
R1 become about 1.2KΩ,and R2 become about 470Ω
(Notice)Please set the load resistance on “fl-out(pin46)” or “fr-out(pin53)” at RL=70KΩ over.
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