An electrical or electronic apparatus designed to convert an input of Alternating Current (AC) voltage into a stable Direct Current (DC) output voltage. This process is critical for operating direct-current semiconductor components and digital circuitry from standard alternating-current power distribution grids.
Linear AC/DC Power Supplies
Linear power supplies operate by stepping down the AC line voltage with a low-frequency transformer, rectifying it, and then using a linear regulator (typically a transistor operating in its linear region) to dissipate excess voltage as heat.
Switched-Mode Power Supplies (SMPS)
An SMPS directly rectifies the high-voltage AC input into a high-voltage DC bus. This DC voltage is then "chopped" or switched at very high frequencies (typically 20 kHz to several MHz) using semiconductor switches (MOSFETs) through a small high-frequency transformer.