There are many kinds of voltage regulator chips, such as 78xx of 78 series, 79xx of 79 series, and the last two digits represent the voltage regulator value; LM series of fixed and adjustable voltage regulation; TL series and many other models. Talk about a series voltage regulator circuit: it is composed of sampling circuit, amplifier circuit, reference voltage, comparison and adjustment tube. For example, a fixed voltage regulator chip has a fixed output voltage within its required input voltage range. Voltage regulation process: When the input voltage becomes higher, the output voltage will increase, and the sampling value of the sampling circuit will also increase. Compared with the reference voltage, the comparator output voltage is reduced to control the adjustment tube to reduce the output voltage.