Wire wound surface mount inductors are passive circuit components, meaning they require an external power source. They have a core made of a magnetic metal like iron with wire wound around it. Energy is stored in a magnetic field when an electrical current flows through the coiled wire which has thick insulation to make the inductors suitable for use with larger currents.
They are typically found in car audio and electronic control units (ECUs) because they can block or filter radio frequencies. Unwanted radio frequencies can interfere with audio sound quality and disrupt electrical circuits. These inductors are also used in electronic equipment used in communication infrastructures and mobile base stations.
This ability to minimise interference makes them ideal for use with DC/DC converters in power distribution systems too.
Some inductors have added magnetic shielding which blocks unwanted magnetism that can interfere with the circuit. Some wire wound inductors are wound with special techniques that enhance performance and reduce the unit size to save space in circuit boards.