The linear regulator controls the tube pressure drop VDO(i.e. pressure difference) of the regulator through a control circuit composed of output voltage feedback and error amplifier, as shown in the figure below. It is characterized by VIN "VOUT, and the regulating tube works in the linear region (hence the name of the linear regulator). When the change of the input voltage or the change of the load current causes the change of the output voltage, the size of the VDO can be changed through the feedback and control circuit, so that the output voltage VOUT is basically unchanged.

Whether it is an ordinary linear regulator or an LDO regulator, the working principle is the same, the difference is that the structure of the two regulators is different, making the LDO have a smaller voltage difference and lower power consumption than the ordinary linear regulator.

Some linear regulators used in LCD TVS have output control terminals. In other words, the output voltage of this voltage regulator is controlled by the control terminal. The following is a block diagram of a controlled voltage regulator. The EN in the figure (sometimes denoted by SHDN) is the output control. Typically, the microprocessor applies a low (or high) level to turn off (or work on) the LDO. When the power is turned off, the power consumption is about 1μA.