LM79xx

LM79xx refers to a family of linear voltage regulator integrated circuits manufactured by National Semiconductor, now part of Texas Instruments. These devices are designed to provide a stable, regulated output voltage from a higher, unregulated input voltage. The LM79xx series is notable for its negative voltage regulation capabilities, meaning it produces a negative output voltage.

The common members of the LM79xx family include devices such as the LM7905, LM7909, and LM7912, which provide fixed negative output voltages of -5V, -9V, and -12V respectively. Other variants exist for different voltage levels. These regulators typically require a minimum input voltage difference to maintain regulation, known as the dropout voltage. They are often used in applications where a negative voltage rail is needed for biasing transistors or other active components, or in power supply designs that require both positive and negative voltage outputs.

Key features of the LM79xx series include internal thermal overload protection and short-circuit current limiting, which help protect the device and the connected circuitry from damage. They are commonly available in TO-220 and TO-3 power packages, suitable for handling moderate power dissipation. The simplicity of their external circuitry, often requiring only a couple of bypass capacitors for stability, makes them a popular choice for many power supply designs.