No. 6630-6/9

LA4743B

Notes on Usage and Handling

• Oscillator stabilization time

In some cases, details of the printed circuit board layout may lead to induced parasitic oscillation. This oscillation can

be prevented by adding any one of the following components. Verify the optimal values for these capacitors by testing

in actual end products.

Technique 1 ... Connect Mylar capacitors (0.1 µF) between the BTL amplifier outputs.

Technique 2 ... Connect an RC circuit (2.2

Ω and 0.1 µF in series) between each output and ground.

• Audio quality (low band)

The low-band frequency characteristics can be improved by adjusting the values of the input capacitors. The

recommended value is 2.2 µF.

• Impulse noise

The LA4743B includes a built-in impulse noise suppression circuit. However, further improvement can be achieved by

using the muting circuit. When first applying power, activate the muting function at the same time as applying power.

Then, after the output DC potential has stabilized, turn off the muting function. When turning off the power, first

activate the muting function and then turn off the power. Sample transient responses are attached (see the timing

charts).

Transient Responses at Power On

Power on: Standby and muting activated at the same time.

Muting is turned off after the output has stabilized.

+

22

3.3

µF

Mute

10 k

Ω

MUTE

MUTE OFF

ON TIME

5 [V]

0

4

2

0

200 ms/div

0 [V]

5 [V]

Transient Responses at Power Off

Power off: After activating the muting circuit, turn the power off.

+

22

3.3

µF

Mute

10 k

Ω

MUTE

200 ms/div

5 [V]

0

4

2

0

0 [V]

5 [V]

Standby set high

External 10 k

Ω muting switch

Standby pin

Output pin

Standby set low

External 10 k

Ω muting switch

Standby pin

Output pin