The LM317 is an adjustable three-terminal positive voltage regulator with a very low dropout of 1.2V at 1.2A output current. Using 2 external resistors, the LM317 can provide an adjustable output voltage down to 1.25V. The LM317 includes a circuit of trimmed bandgap reference to assure output voltage accuracy to be within 1%. It also provides current limiting and thermal shutdown. The current limit is trimmed to ensure specified output current and controlled short-circuit current. The On-chip thermal limiting provides protection against any combination of overload and ambient temperature that would create excessive junction temperature.