The LLM317 is a three-terminal tunable positive voltage regulator integrated circuit from National Semiconductor. The M317 has an output voltage range of 1.2V to 37V with a maximum load current of 1.5A. It is very simple to use, only two external resistors to set the output voltage. In addition, its linear adjustment rate and load adjustment rate are better than standard fixed regulators. The LM317 has built-in overload protection, safety zone protection and other protection circuits. Generally, an external capacitor is not required for the LM317 unless the connection between the input filter capacitor and the LM317 input is more than 6 inches (about 15 cm). The transient response can be changed using the output capacitance.