Switching transformer are transformers which run on direct current supply that is switched at a designated time rate. A step-down transformer is required to lower the potential difference within the power outlet. Switching transformers attain this by quickly turning the current on and off, changing the current to a higher frequency. They can have multiple secondary windings and in turn many electrically independent outputs. Pulse width modulation is applied to control voltage.

The design of switching transformers vary based on the type of circuit employed. Three examples of circuit layouts would be the forward converter (Buck) circuit and Inductive Flyback (kickback) circuits.

A benefit of using such transformers are that little power is emitted beyond its active region. This gives rise to its high efficiency. Other benefits include its compactness, light weight and minimized heat dissipation. However, it may also have drawbacks in the form of high complexity, creation of high-amplitude and high-frequency energy which requires a filters to block off electromagnetic interference.