A linear voltage regulator IC provides a stable, low-noise DC output voltage from a higher, fluctuating input. It acts as a variable resistor to dissipate excess power as heat. These ICs require only a few external components and are ideal for noise-sensitive, low-current circuits. Because they operate linearly, their efficiency is calculated as (V_{out}/V_{in}). This means power efficiency can range from about 16% to 66%, dropping lower as the gap between input and output voltage increases.