LA5511 principle block diagram and typical application circuit

Its working principle is briefly described as follows: When the power supply voltage vcc changes or the mechanical load of the motor
changes, it will cause the motor speed to change. The back electromotive
force E is proportional to the rotational speed. As the marrow changes, the voltage across the motor also changes accordingly .
The voltage v sampled from the two points of the adjustable resistors 1 and 4. These voltage changes are reflected and sent to
the non-inverting input terminal of the error amplifier. It is compared with the reference voltage VREF at the inverting input terminal.
After the error is amplified , the bases of the two transistors are controlled, and the output voltage (pin 3) is adjusted. The output voltage of pin 3
is V. . It has a negative feedback control relationship, and the closed-loop control result tends to maintain a constant speed.