No.8178-4/8

LA4632

Application Circuit Example/Test Circuit Diagram

+

RF

+

IN1

+

IN2

+

MUTE

PWR

GND

+OUT2

--OUT2

--OUT1

STBY

VCC

VCC

PRE

GND

+

+OUT1

LA4632

1

2

3

4

5

6

7

10

11

12

RL

RL

8

9

Top view

• Caution

Although the LA4632 is basically pin compatible with the LA4631, there are certain differences in the external

components and the way the devices are used.

External Components and Usage Notes

C1, C2: These are input coupling capacitors; we recommend a value of 4.7 µF or lower. A zero bias type circuit is

used for the LA4632 input circuits, and the input pin potential is close to zero volts. Therefore the polarity

must be considered in conjunction with the DC potential of the circuit connected to the LA4632 front end.

If there is a large potential difference between the plus and minus sides of the input capacitors, the

stabilization time when power is first applied can be reduced by reducing the value of the input

capacitors, as long as that reduction does not compromise the low-band characteristics.

C3:

This capacitor is used both as a ripple filter and to set the amplifier's startup time. A value of 47 µF is

recommended. With this value, the startup time (the time from the point power is first applied until the

point an output is generated) will be about 0.6 to 0.7 seconds. (See note 1.)

C4, R1: This RC circuit is used for mute smoothing. C4 is required even if the muting function is not used. (See

note 2.)

C5:

Power supply capacitor

C6 to C9, R2 to R5: These components form oscillation prevention RC circuits. We recommend using polyester

film capacitors (Mylar capacitors) with excellent thermal characteristics for C6 through C9. (R2 to R5 are

2.2

Ω 1/4 W resistors.)

*1. Startup time

The LA4632 features a built-in startup circuit that can be adjusted somewhat by changing the value of the capacitor

connected to pin 1. (With the recommended value of 47 µF, the time is about 0.6 to 0.7 seconds (a time that changes

10 µF in parallel.) Since using a capacitor with a value smaller than the recommended value may reduce the SVRR

between ground and the output, we cannot recommend using a smaller value.

*2. Signal muting function

The signal muting function is turned on by connecting the recommended RC circuit (10 µF, 15 k

Ω) to pin 6 and

applying a voltage of +5 V to the mute pin. This circuit implements a muting function with extremely low impulse

noise.

This RC circuit is used to smooth the attack and recovery times, and since the 10 µF capacitor also has the function

of smoothing after the startup time, it is required even if the signal muting function is not used.