Also referred to as 3-terminal regulator or dropper, the linear regulator, due to a simple circuit structure and ease of use, is a power supply that has been familiar to many designers for decades. Although the very old linear regulators were configured with discrete parts, the increasing integration into IC has led to more simplified and smaller linear regulators. This has made them well-suited for a wide variety of power supply applications. In recent years, a paramount requirement for electronic devices has been high efficiency. Despite the fact that in devices requiring large output power, switching power supply units are becoming predominant, linear regulators, simple in structure with small footprints, and best of all, of low-noise attributes, are found to meet the needs for power supply in virtually every niche.
This section provides the operating principles of the linear regulator, and describes its main specifications and thermal calculation.