
No. 6629-6/9
LA4743A
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 F) between the BTL amplifier outputs.
Technique 2 ... Connect an RC circuit (2.2 and 0.1 F 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 F.
Impulse noise
The LA4743A 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 F
Mute
10 k
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 F
Mute
10 k
MUTE
200 ms/div
5 [V]
0
4
2
0
0 [V]
5 [V]
Standby set high
External 10 k muting switch
Standby pin
Output pin
Standby set low
External 10 k muting switch
Standby pin
Output pin