
LA47516
No.8307-4/7
Description of Operation
1. Standby switch function (pin 4)
The pin 4 threshold voltage is set to 2VBE; the amplifier turns on when Vst = 2.0V or higher, and off when Vst = 0.7V
or lower. Note that pin 4 requires an operating current of 40
A or higher.
Note : Do not ground the output with the Pin 4 voltage at approximately 1.4V. In addition, do not give the Pin 4
voltage a time constant.
2. Muting function
The audio can be muted by connecting pin 22 to ground through a 10k
resistance. This sets the IC to the muted state.
The mute time constant is determined by the external capacitor and resistor constants. The recommended external
constants are C = 3.3
F, R = 10k.
3. Oscillation stability
Parasitic oscillation may be induced depending on the board layout.
Countermeasures against oscillation can be taken by adding the following parts.
Note that the following are only examples for reference, and that the optimum capacitance values must be confirmed
in the mounted condition for each set.
Connect a Mylar capacitor (0.033F) between the BTL outputs.
Connect a capacitor and a resistor (0.1F and 2.2 in series) between each output and GND.
4. Sound quality (low frequencies)
The frequency response in the low frequency range can be improved by varying the capacitance value of the input
capacitor. The recommended value is 2.2
F or less.
5. Impulse noise
This IC includes a function for preventing impulse noise from appearing in the output. The effect of this function can
be improved by using it in combination with the muting function.
When turning on the amplifier, turn the power supply and the mute function on at the same time.
Then turn the mute function off after the output current potential has stabilized.
When turning off the amplifier, first turn on the muting function and then turn off the power.
6. Electric mirror noise suppression measures
A capacitor about twice the size of the input capacitors must be used for the capacitor between pins 1 and 25 that is
used to minimize noise from the electrically driven mirror.
In the sample application circuit, a 0.47
F capacitor is used for 0.22F input capacitors.
Note that the capacitor connected between pins 1 and 25 must be connected to the same pre-ground as the input
capacitors.