The LM317LIPK from Texas Instruments is a 3-pin, 100mA adjustable voltage linear regulator. It is used to regulate an input voltage of up to 40 volts down to an output voltage as low as 1.2 volts and as high as 37 volts. Popular applications include LED lighting, low-voltage power supply circuits, battery charging and many others. Its features include higher efficiency, temperature stability, low noise, short-circuit protection, thermal shutdown, and current limiting.