Power Supplies & Voltage Controllers - Linear Regulators

Linear regulators maintain a constant voltage output. They act like a variable resistor, continuously adjusting a voltage divider network to maintain a constant output voltage and continually dissipating the difference between the input and the output as waste heat. 

A linear regulator steps down a higher voltage on the input to a lower voltage on the output. This is similar to a buck converter, except a buck converter will waste much less power. So if the input voltage is much higher than the desired output voltage a buck regulator is usually preferable to a linear regulator.

As a general rule, linear regulators are ideal for applications that require low noise and a very stable output voltage, whereas switching power supplies are better suited for portable and battery-powered devices where battery life and efficiency are important.