Unlike linear power supplies, switching power supplies utilize switching transistors that typically toggle between a fully-on mode (saturation region) and a fully-off mode (cutoff region). Both of these modes are characterized by low power dissipation; while the transitions between switching states involve higher dissipation, they occur over very brief durations. Consequently, switching power supplies are more energy-efficient and generate less waste heat. Ideally, a switching power supply itself consumes no electrical energy. Voltage regulation is achieved by adjusting the duration for which the transistor remains in the conducting (on) or non-conducting (off) state. Conversely, during the process of generating an output voltage, a linear power supply operates its transistors within the amplification region, thereby consuming electrical energy itself. The high conversion efficiency of switching power supplies constitutes one of their primary advantages. Furthermore, due to their high operating frequencies, switching power supplies can utilize smaller and lighter transformers; as a result, they are generally more compact and lighter in weight than their linear counterparts.
When high efficiency, compact size, and light weight are key design priorities, switching power supplies are preferable to linear power supplies. However, switching power supplies are inherently more complex; their internal transistors switch frequently, and if the associated switching currents are not properly managed, they may generate electrical noise and electromagnetic interference that could adversely affect other equipment. Additionally, unless specifically designed to address this issue, a switching power supply may exhibit a relatively low power factor.
