LM317

The LM317 is a popular adjustable linear voltage regulator. It was designed by Robert C Dobkin in 1976 while he worked at National Semiconductor.

The LM337, a negative complement to the LM317, regulates voltages below, rather than above, the reference. It was designed by Robert "Bob" Pease.

Specifications

Operation

As linear regulators, the LM317 and LM337 are used in DC to DC converter applications.

Linear regulators inherently draw as much current as they supply. When this current is multiplied by the voltage difference between input and output, a significant amount of heat results. Therefore the use of an LM317 commonly also requires a heat sink. For large voltage differences, the energy lost as heat can ultimately be greater than that provided by the circuit. This is the trade-off for using linear regulators which are a simple way to provide a stable voltage with few additional components. The alternative is to use a switching voltage regulator which is usually more efficient but has a larger footprint and requires a larger number of associated components.