STK301-220 Sanyo Semiconductor Corporation, STK301-220 Datasheet - Page 5

• Manufacturer Part Number: STK301-220
• Description: 7-band, 2-channel Electronic Equalizer
• Manufacturer: Sanyo Semiconductor Corporation

Pins f (1) through f (7) are used as pin connections for the
LC7522 band filter. Supported frequencies and their pin
assignments are listed in the following.
In order to minimize the noise which occurs during changeover,
connections are made using 1 MΩ resistors from pins f (1)
through f (7) to 1/2 V
Principles of Operation
The graphic equalizer section is constructed from 7 resonance circuits and output buffer amplifiers (every channel);
variable resistors (LC7522) and resonance circuit capacitors C1 and C2 are built-in. Resonance circuits utilize
semiconductor inductors and apply resonation to reduced impedance; all frequency gains are altered.
1. Resonance Circuit
2. Flat, Boost and Cut
Semiconductor inductors replace the L of the R, L, C series
resonance circuit with a CR element passing through the
buffer function of active elements such as the transistor and
op-amp (operational amplifier), thereby effecting the
equivalent operation of a R, L, C series resonance circuit.
The STK301-220 resonance circuit buffer is constructed
using transistors and arranged as illustrated in Figure 2.
Resonance frequency fo is determined using the following
formula:
Gains matching resonance circuit frequency gains are altered
by altering the built-in resonance circuits and electronic
volume control. Figure 3 is presented to describe the
equivalent circuit. Z represents the impedance of the
resonance circuit in Figure 2.
Pin Name
fo =
f (1)
f (2)
f (3)
f (4)
f (5)
f (6)
f (7)
2
C1 · C2 · R1 · R2
CC
Frequency
1.
2.5kHz
150Hz
400Hz
15kHz
60Hz
1kHz
6kHz
1
STK301-220
Resistor Equivalent Circuit
Figure 2 Resonance Circuit
Figure 3 Equivalent Circuit
(single band)
No. 4793-5/8