Popular 7812 regulator IC

The popular 7812 regulator IC is a three terminal positive voltage regulator IC which provides a stable output. While 7805 IC provides a steady 5V DC output, 7812 provides a 12V DC output. Input DC voltage can range from 14V to 35V. It can supply a continuous current of up to 1A or 1.5A. There is internal thermal overload and short-circuit current limit protection built-in within the integrated circuit. Minimum dropout voltage is 2-2.5V, meaning that it requires an input voltage of 2-2.5V above 12V for functioning properly. It has TO-220 through-hole and surface mount packages like TO-152. The one shown here is through-hole mounting type.

As the voltage dropped is dissipated as heat, especially when the voltage difference between input and output is large, a heat sink is desirable to prevent overheating. Here a heat sink has been screwed on to the IC 7812. Unregulated DC power supply is connected to the input pin, ground is connected to the ground pin and output pin is connected to the load. It provides a clean, linear regulated DC output, which is ideal for noise-sensitive applications like audio amplifiers and sensor interfaces. Efficiency is lower than switching regulators as the dropped voltage is lost as heat. Suppose 18V input is converted to 12V output, 6V drop at 1A load current can cause 6W of power wastage. Heatsink is needed if the current is more than 300-350 mA.

A capacitor of the order of 0.33µF or larger at the input (between Pin 1 and Pin 2) can filter high frequency noise. 0.1µF or larger capacitor at the output (between Pin 2 and Pin 3) improves the transient response and stabilizes the output voltage, preventing oscillation.