The linear regulator controls the stability of the output voltage by reference voltage and variable resistance. When the input voltage changes, the feedback circuit senses and transmits the change signal to the regulator.
The voltage regulator changes the output voltage by adjusting the current of the variable resistor to keep it at a predetermined stable value.
The reference voltage is usually provided through a reference voltage source and is compared with the input voltage. If the output voltage drops, the feedback circuit increases the current of the regulator, raising the output voltage, and vice versa. This feedback mechanism ensures the stability of the output voltage within the range of the input voltage.