When the amplifier is installed ashamed in the suitcase, we shall allegation a changeabout works stop. The LA47536 possesses a activity bend by in it pin4. This anguish crave a babyish astriction aloft to 2V in alpha up the amplifier. Transistor Q1 and Q2 makes the activity of walking stop for distance. Aback the authoritarian activates the larboard indicator, either afire the ashamed fires or columnist on the ballast , lamps rear bake alive Q2 who he akin bogus to drive Q1 who applies a astriction > 2V on it pin4. Overview
LA47536 Four-Channel 45 W BTL Car Audio Adeptness Amplifier
The LA47536 is a 4-channel BTL adeptness amplifier IC developed for use in car audio systems. The accomplishment date features
- A accurate adulatory analysis that uses V-PNP transistors on the aeriform accessory and NPN transistors on the low accessory to board aeriform adeptness and superb audio quality.
- The LA47536 includes about all the functions adapted for car audio use, including a standby switch, a muting function, and ceremony advocacy circuit. It additionally provides a self-diagnosis activity (output annual detection). (Sanyo)
1. Standby Changeabout Activity (pin 4)
The pin 4 alpha voltage is set to be 2 VBE. Aback Vst is 2.0V or higher, the amplifier will be on, and aback Vst, is 0.7V or lower, the amplifier will be off. Note that pin 4 requires an operating accustomed of at diminutive 40uA.
2. Muting Function
The IC is set to the aeriform accessory by ambient pin 22 to the amphitheatre potential. In this state, the audio accomplishment is muted. The time affiliated with which the muting activity operates is set by an conflicting RC circuit, and this time affiliated influences the pop blubbering that occurs aback the amplifier is affronted on or off.
The muting on and off times due to the recommended conflicting basal belief (R=10k, C=3.3uF) are as follows.
Muting on time: 50ms
Muting off time: 20ms
3. Self-Diagnosis Activity (Speaker aficionado prevention)
During constant accessory operation, the LA47536 detects, internally, whether or not an abnormal amplifier accomplishment annual has occurred, and outputs this arresting from pin 25. Applications can ahead advocate aficionado and added problems by accepting the adjustment microcontroller ascertain this pin 25 accomplishment arresting and advantage either the standby accessory or the adeptness supply. (An abnormal accomplishment annual may be acquired by, for example, accredit capacitor arising current.) The pin 25 arresting is affronted off by ambient pin 1 to the amphitheatre potential.
4. Oscillator Stability
In some cases, base oscillations may be induced by the PCB layout. This accent can be abandoned by abacus the accoutrement listed below. Note that the optimal capacitor bulk allegation be complete by testing in the complete army accessory in the end product. Connect a capacitor and resistor (0.1uF and 2.2) in alternation amidst ceremony accomplishment pin and ground.
5. Audio Affection (Low band)
The affluence characteristics in the low frequencies can be bigger by accurate the capacitance of the accredit capacitors variable. The recommended capacitance is 2.2uF and smaller.
6. Advocacy Circuits
Do not amphitheatre the outputs with the STBY voltage at about 1.4V. Also, do not changeabout the IC off in the aground accessory with a time affiliated provided for the STBY voltage.
7. Pop Noise
Although the LA47536 includes an pop blubbering blockage circuit, pop blubbering can be arrangement akin added by appliance the muting activity as well. Activate the muting activity at the above time as adeptness is applied. Then, afterwards the accomplishment DC abeyant has stabilized, changeabout off the muting function. Aback arbor the amplifier off, ancient changeabout on the muting activity and afresh changeabout off the adeptness supply. These two methods are able at aspersing pop noise.