A switching mode power supply is an electronic power supply that incorporates a switching regulator to convert electrical power efficiently,. Like other power supplies, as SMPS transfers power a DC or AC source (often mains power) to DC loads, such as a personal competer, while converting voltage ans current charateristics. Unlike a linear power supply, the pass transistor of a switching mode power supply continually switches between low-dissipation, full-on and full off states, and spends very little time in the high dissipation transitions, which minimizes wasted energy. Ideally, a switching power mode power supply dissipates no power. Voltage regulation is achieved by varying the tatio of on-to-off time. In contrast, a linear power supply regulates the output voltage by continually dissipating power in the pass transistor. This higher power conversion efficiency is an important advantage of a switching mode power supply. Switching mode power supplies may also be substantially smaller and lighter that a linear supply due to the similar transformer size and weight.
Switching regulation are used as replacements for linear regulations when higher efficiency, smaller size or lighter weight are required. They are. however. more complicated: their switching currents can cause electrical noise problems if not carefully suppressed, and simple designs may have a poor power factor.
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