The outstanding advantages of linear regulators are the lowest cost, the lowest noise and the lowest static current. It also has very few peripherals, usually only one or two bypass capacitors. The new linear regulator achieves the following: 30V output noise, 60dB PSRR, 6A static current and 100mV voltage difference. The main reason that linear regulators can achieve these characteristics is that the internal regulator uses a P-channel FET instead of the PNP transistor in the usual linear regulator. P-channel FET does not require base current drive, so the current of the device itself is greatly reduced. On the other hand, in the PNP transistor structure, in order to prevent the PNP transistor from entering saturation and reducing its output capacity, it is necessary to ensure a large input and output voltage difference; However, the voltage difference of a P-channel FET is roughly equal to the product of the output current and its on-resistance, and since its on-resistance is very small, its voltage difference is very low. When the input voltage and output voltage in the system are close, the linear regulator is the best choice and can achieve high efficiency. Therefore, in the application of converting the voltage of a lithium-ion battery to a 3V voltage, most linear regulators are used. Although 10% of the battery's final discharge energy is not used, a linear regulator can still provide long battery life in a low-noise structure.