lc75421m Sanyo Semiconductor Corporation, lc75421m Datasheet - Page 15

• Manufacturer Part Number: lc75421m
• Description: Electronic Volume Controller For Cars
• Manufacturer: Sanyo Semiconductor Corporation

Tone Circuit Constant Calculation Examples
Super Bass Band Circuit
• Super bass band equivalent circuit block diagram
• Calculation example
Specification Mean frequency: f0 = 68 Hz
We obtain R3 from G = 20 dB.
We obtain C from mean frequency f0 = 68 Hz.
We obtain Q.
The equivalent circuit and the formula for calculating the external RC with a mean frequency of 68 Hz are shown
below.
C
G
R3
f 0
+20 dB
Q
2 f0 R3R2
2 10
2
R3R2
2R3
20 LOG
1
R3R2C1C2
G+20dB/20
Gain during maximum boost: G = 20 dB
Let us use R1 = 0, R2 = 66.6 kΩ, and C1 = C2 = C.
R2
1
R3R2
1
–1
10
2
1
2 (10 – 1)
2.1
68 66600 3700
2R3
R2
66600
1
3.7 K
C1
0.15 F
R1
LC75421M
R3
R2
C2
No. 6866-15/24