Guide and Resources page for Power Electronics
Basics of smps switching power supply / switching mode power supply design:

Circuits, schematics, electrical engineering reference, software and other info

In practical, electric energy is not used in the form in which it was produced or distributed, all electronic systems require some form of energy conversion. The device to convert electric energy from source to load via electronic circuits is referred to as Power Supply (although "power converter" is a more accurate term for that device).

Power supply unit (PSU) usually works to convert utility AC voltage into regulated DC voltages to be used by the equipment. In most PSU, the energy flow is controlled with semiconductors which are continuously switching on and off with high frequency. Such kind of PSU are referred to as switch mode power supplies or SMPS. Using switches to control energy flow create lower losses and thus SMPS offer higher efficiency when compared with linear power supplies. This is true because when a switch is on the current is passed with a low voltage while it is off, current is blocked. In both states the power loss or power dissipation is relatively low. SMPS have smaller number of passive components and lower heat generation (due to less power loss), thus SMPS can be smaller in size and is lighter in weight in general. “Switching mode” is now the dominant type of PSU in almost every spectrum of applications. PFC front end in AC input is found in almost every AC input application.