A DC-DC converter is an energy conversion system that transforms one direct voltage into another by using rapid switching of the power supply, typically via a MOSFET, in order to temporarily store energy in an inductor or capacitor, and then return it in a controlled manner to the load.

The output voltage does not result from a direct transformation, but from the energy balance imposed by the duty cycle, the load, and the control loop. This approach allows for high efficiencies by minimizing losses due to dissipation, while ensuring a stable voltage despite variations in load or input voltage.

The most common topologies include non-isolated converters such as buck (step-down), boost (step-up), and buck-boost architectures (SEQIP, Ćuk) for variable input voltages, as well as isolated converters like flyback, forward, or half-bridge/full-bridge structures for higher power levels and safety constraints. Depending on the application, the choice of topology allows for the optimization of efficiency, complexity, isolation, and power capacity.