Editing Linear regulator (section)

==Variable regulators==
{{Expand section|date=October 2012}}

An adjustable regulator generates a fixed low nominal voltage between its output and its adjust terminal (equivalent to the ground terminal in a fixed regulator). This family of devices includes low power devices like '''LM723''' and medium power devices like '''[[LM317]]''' and '''L200'''. Some of the variable regulators are available in packages with more than three pins, including [[dual in-line package]]s. They offer the capability to adjust the output voltage by using external resistors of specific values.

[[File:Low Drop Voltage Regulator.png|right|thumb|162 px|Adjustable voltage regulator circuit showing 'adjust' terminal]]

For output voltages not provided by standard fixed regulators and load currents of less than 7 A, commonly available adjustable three-terminal linear regulators may be used. The '''LM317''' series (+1.25&nbsp;V) regulates positive voltages while the '''LM337''' series (−1.25&nbsp;V) regulates negative voltages. The adjustment is performed by constructing a potential divider with its ends between the regulator output and ground, and its centre-tap connected to the 'adjust' terminal of the regulator. The ratio of resistances determines the output voltage using the same feedback mechanisms described earlier.