LA4266

No. 7091-3/6

Description of External Parts

C1: Ripple filter capacitor

Decreasing the capacitance value reduces ripple rejection. This capacitor also affects the starting time; decreasing

the capacitance value makes the starting time earlier.

C2: Input capacitor

Because the DC potential of the input pin is not zero, this capacitor can not be omitted. Decreasing the capacitance

value to an extremely low level lowers the low frequency response.

C3: Feedback capacitor

Decreasing the capacitance value lowers the low frequency response. Increasing the capacitance value makes the

starting time later.

C4: Output capacitor

Decreasing the capacitance value causes insufficient power at low frequencies.

C5: Oscillation blocking capacitor

Decreasing the capacitance value causes oscillation to occur easily. Use a polyester film capacitor that has good high

frequency response and temperature characteristics.

The use of an electrolytic capacitor or a ceramic capacitor may cause oscillation to occur at low temperatures.

C6: Power capacitor

Decreasing the capacitance value causes ripple to occur easily. Locating at a distance from the IC or removing this

capacitor may cause oscillation to occur.

R1: Mute resistor

Refer to supplementary discussion “External Muting.’’

R2: Resistor connected in series with oscillation blocking capacitor

Prevents phase shift in conjunction with the oscillation blocking capacitor so that oscillation does not easily occur.

There is an optimal value for the resistor; increasing or decreasing the resistance causes oscillation to occur easily.

External Muting

• Pull down the electric potential of the ripple filter pin (pin 3).

Muting becomes possible by inserting the discharge resistor R1 between pin 3 and

GND. If the resistance value of R1 is too low, a popping noise is generated; if the

resistance value is too high, the muting effect is reduced. (A value of 750

Ω is

recommended for R1.)

Voltage Gain

The voltage gain is fixed at 40dB by the ratio of the 30 k

Ω and 300 Ω

internal resistors. Therefore, it is not possible to use this IC with a

voltage gain greater than 40 dB. Although it is possible to use this IC

with a voltage gain of less than 40 dB by adding a feedback resistor

(RNF) and external resistors (R) as shown in the diagram, doing so

causes oscillation to occur easily. Therefore, do not use this IC with a

voltage gain of 30dB or less.

+

NC

Filter

C1

R1

2

3

4

Mute SW

PRE GND

+

+

+

30 k

Ω

IN

Rf

OUT

5

6

7

R2

RL

C4

C5

C2

R

C3

NF

RNF