LA47536 Ver la hoja de datos (PDF) - SANYO -> Panasonic
Número de pieza
componentes Descripción
Fabricante
LA47536 Datasheet PDF : 7 Pages
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LA47536
Functional Description
1. Standby Switch Function (pin 4)
The pin 4 threshold voltage is set to be 2 VBE. When Vst is 2.0V or higher, the amplifier will be on, and when Vst is
0.7V or lower, the amplifier will be off. Note that pin 4 requires an operating current of at least 40µA.
2. Muting Function
The IC is set to the muted state by setting pin 22 to the ground potential. In this state, the audio output is muted. The
time constant with which the muting function operates is set by an external RC circuit, and this time constant
influences the pop noise that occurs when the amplifier is turned on or off.
The muting on and off times due to the recommended external component values (R=10kΩ, C=3.3µF) are as follows.
Muting on time: 50ms
Muting off time: 20ms
3. Self-Diagnosis Function (Speaker burnout prevention)
During steady state operation, the LA47536 detects, internally, whether or not an abnormal amplifier output offset
has occurred, and outputs this signal from pin 25. Applications can prevent speaker burnout and other problems by
having the system microcontroller detect this pin 25 output signal and control either the standby state or the power
supply. (An abnormal output offset may be caused by, for example, input capacitor leakage current.)
The pin 25 signal is turned off by setting pin 1 to the ground potential.
4. Oscillator Stability
In some cases, parasitic oscillations may be induced by the PCB layout. This oscillation can be eliminated by adding
the components listed below. Note that the optimal capacitor value must be verified by testing in the actual mounted
state in the end product.
• Connect a capacitor and resistor (0.1µF and 2.2Ω) in series between each output pin and ground.
5. Audio Quality (Low band)
The frequency characteristics in the low frequencies can be improved by making the capacitance of the input
capacitors variable.
The recommended capacitance is 2.2µF and smaller.
6. Protection Circuits
Do not ground the outputs with the STBY voltage at around 1.4V. Also, do not turn the IC off in the grounded state
with a time constant provided for the STBY voltage.
7. Pop Noise
Although the LA47536 includes an pop noise prevention circuit, pop noise can be reduced even further by using the
muting function as well.
• Activate the muting function at the same time as power is applied. Then, after the output DC potential has
stabilized, turn off the muting function.
• When turning the amplifier off, first turn on the muting function and then turn off the power supply.
These two methods are effective at minimizing pop noise.
No.7901-3/7
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