In DC/DC switching circuits, appropriately driven electronic switches and components are used to store energy, allowing it to be converted. A step-down, or buck, converter is a DC/DC power converter that reduces the input voltage and provides a lower output voltage.

A buck converter or step-down converter is a DC-to-DC converter which decreases voltage, while increasing current, from its input (supply) to its output (load). It is a class of switched-mode power supply.

DC-DC step-down converters basically take a higher input voltage and converts it to a lower output voltage by chopping it up by rapidly switching the output power transistor on and off so that the output essentially looks like a square wave and then using an LC filter to smooth it back into a DC voltage on the output of the filter.

Buck converters reduce the voltage of a power supply. This is a power electronics circuit that steps down the DC voltage to a level determined by the choice of components in your circuit. Unlike linear regulators that reduce the voltage by dissipating power as heat, buck converters reduce the voltage by increasing the current.