As linear regulators, the LM317 and LM337 are used in  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 power is wasted as heat. This is not just inefficient, but a significant design consideration; a heat sink is commonly required. For  large voltage differences, the wasted power can be more than the power supplied. This trade-off must be accepted when using linear regulators, which are a simple way to provide a stable voltage with few additional components. The alternative is to use a , which is usually more efficient, but tends to take up more space and require a higher component count.

In packages with a heat-dissipating mounting tab, such as , the tab is connected internally to the output pin, which may make it necessary to electrically isolate the tab or the heat sink from other parts of the application circuit.