150W MP3 Car Amplifier

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Circuit : Youssef BouterfesEmail : [email protected]

Block Diagram:Here, it is a diagramm of an active loudspeaker. The LF353 of, National Semiconductor, is going

to split audio signal into three bands. SANYO'S LA47536 is going to amplify these signals. Instereo mode, we shall have the action of eight high speakers who are going to create a very

important sound pressure.

Three Band Active Tone Control:

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W MP3 Car Amplifier http://www.zen22142.zen.co.uk/Circuits/Audio/150w

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Description :LF353 Wide Bandwidth Dual JFET Input Operational AmplifierGeneral Description

These devices are low cost, high speed, dual JFET input operational amplifiers with an internallytrimmed input offset voltage (BI-FET II technology). They require low supply current yet

maintain a large gain band width product and fast slew rate. In addition, well matched highvoltage JFET input devices provide very low input bias and offset currents. The LF353 is pincompatible with the standard LM1558 allowing designers to immediately upgrade e the overallperformance of existing LM1558 and LM358 designs. These amplifiers may be used in

applications such as high speed integrators, fast D/A converters, sample and hold circuits andmany other circuits requiring low input offset voltage, low input bias current, high input

impedance, high slew rate and wide bandwidth. The devices also exhibit low noise and offsetvoltage drift. (National Semiconductor)

Features :Internally trimmed offset voltage: 10 mVLow input bias current: 50pALow input noise voltage: 25 nV

Low input noise current: 0.01 pAWide gain bandwidth: 4 MHzHigh slew rate: 13 V/us

Low supply current: 3.6 mHigh input impedance: 1012.

Low total harmonic distortion : < 0.02%Low 1/f noise corner: 50 HzFast settling time to 0.01%: 2 us


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Power Amplifier :

When the amplifier is installed behind in the suitcase, we shall need a switch works stop. TheLA47536 possesses a function stand by in it pin4. This pine require a small tension superior to

2V in start up the amplifier. Transistor Q1 and Q2 makes the function of walking stop fordistance. When the driver activates the left indicator, either light the back fires or press on thebrake , lamps rear ignite driving Q2 who he even made to drive Q1 who applies a tension > 2Von it pin4.

LA47536 Four-Channel 45 W BTL Car Audio Power AmplifierThe LA47536 is a 4-channel BTL power amplifier IC developed for use in car audio systems. Theoutput stage features

- A pure complimentary structure that uses V-PNP transistors on the high side and NPNtransistors on the low side to provide high power and superb audio quality.

- The LA47536 includes almost all the functions required for car audio use, including a standby

switch, a muting function, and each protection circuit. It also provides a self-diagnosis function(output offset detection). (Sanyo)

Functional Description1. 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


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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 40uA.

2. Muting FunctionThe 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 externalRC 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=10k,C=3.3uF) 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 abnormalamplifier output offset has occurred, and outputs this signal from pin 25. Applications canprevent 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 abnormaloutput offset may be caused by, for example, input capacitor leakage current.) The pin 25 signalis turned off by setting pin 1 to the ground potential.

4. Oscillator StabilityIn some cases, parasitic oscillations may be induced by the PCB layout. This oscillation can beeliminated 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 andresistor (0.1uF and 2.2) 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 capacitanceof the input capacitors variable. The recommended capacitance is 2.2uF 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 inthe 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 evenfurther by using the muting function as well. Activate the muting function at the same time aspower 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 powersupply. These two methods are effective at minimizing pop noise.

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150W MP3 Car Amplifier

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