LV4991TT

No.A0739-6/11

Cautions for use

1. Input coupling capacitor (C3)

The input coupling capacitor C3 and input resistor R1 make up the high-pass filter, attenuating the bass frequency.

Therefore, the capacitance value must be selected with due consideration of the pass band. Note with care that this

capacitance value affects the pop sound at startup.

Namely, the increased capacitance value will make the pop sound louder.

2. Pin 3 capacitor (C4)

This capacitor C4 is designed to reduce the power ripple. The ripple removal ratio increases when the capacitance is

larger. Note however that this capacitor affects the pop sound at startup.

Design must therefore be made by taking into both features as above described.

3. Pin 4 control (second amplifier stop control function)

Pin 4 is a pin to turn ON/OFF the operation of second amplifier. By using this function, the pop sound at startup can be

reduced. Note that pin 4 can be controlled by applying the voltage described below :

Second amplifier ON

⇒ V4 = 1.6 to VCCV or OPEN

Second amplifier OFF

⇒ V4 = 0 to 0.3V

When the pin-3 capacitor C4 is downsized, the pop sound becomes louder. The pop sound can be reduced by providing

the time Tmu to stop the second amplifier (see Fig. 1) while utilizing this function of the microcomputor. The

recommended mute time Tmu is as follows.

C4 [

µF]

0.1

0.22

0.33

Tmu [ms]

≥ 170

≥ 270

≥ 280

Fig. 1

4. Standby pin (pin 2)

By controlling the standby pin, the mode changeover can be made between standby and operation modes.

Standby mode

⇒ V2 = 0 to 0.3V

Operation mode

⇒ V2 = 1.9 to VCCV

When using the standby pin as interlocked with power supply as shown in Fig. 2, care should be taken because the

current ISTBY as expressed by the following equation flows through the standby pin.

ISTBY =

VCC−1.4V

R3+21k

Ω

Fig. 2

VCC

R3

VCC

STBY

7

2

Pin 2:STBY

Pin 4:CNT

Between pins 8 and 5:

OUT1-OUT2

Tmu

time

AMP2:ON