lc75397e Sanyo Semiconductor Corporation, lc75397e Datasheet - Page 19

• Manufacturer Part Number: lc75397e
• Description: Single Chip Electronic Volume And Tone Control System
• Manufacturer: Sanyo Semiconductor Corporation

External Capacitor Calculations
1. Bass circuit
The value of the external capacitor used by the LC75397E bass control can be calculated as shown in the example below.
Sample calculation: For a center frequency f0 of 39 Hz
Assume C1 = C2 = C.
C = ——————
C = ———————————
Formula for calculating the gain:
R1 = 1.3 k
R2U = 1.476 k
R2L = 56.517 k
G = (—————)
Formula for calculating Q:
Q = ——————————————
2
2 f0 R1R2
(R1 + R2U) R1 (R2U + R2L)
R1 + R2U
39
R1
1
R1 (R2U + R2L)
1300 58000
1
2
Substitute the LC75397E internal resistors R1 and R2 shown below into the above formula.
This allows the value of the capacitor, C, to be calculated.
+ (—————————————)
R1 = 1.3 k
R2 = 57.993 k
(R1 + R2U) R1 (R2U + R2L)
R1 (R2U + R2L)
0.47 µF
G
LC75397E
2
= 3.16 = 10 dB
No. 6108-19/26