Switch mode power supplies, SMPS provide improved efficiency & space saving over traditional linear supplies, but care has to be taken to ensure noise on the output is low.?
Switch mode power supplies are widely used because of the advantages they offer in terms of size, weight, cost, efficiency and overall performance.

As a result of their performance, switch mode power supplies are used in all but the most exacting applications to provide an efficient and effective source of power for most forms of electronic systems.

Switch mode power supplies have become an accepted part of the electronics scene and are often referred to as switch mode power converters, or just switchers.

Switch mode power supply terminology

Switch mode power supply, SMPS, technology may be referred to by a number of similar terms. While they all look at the same basic technology, they refer to different elements of the overall technology:

Switch mode power supply, SMPS: ? The term switch mode power supply is generally used to indicate an item that can be connected to the mains, or other external supply and used to generate the source power. In other words it is a complete power supply.
Switch mode regulator: ? This typically refers just to the electronic circuit that provides the regulation. A switch mode regulator will be part of the overall switch mode power supply.
Switch mode regulator controller: ? Many switch mode regulator integrated circuits do not contain he series switching element. This will be true if the current or voltage levels are high, because an external series switching element would be able to better handle the higher current and voltage levels, as well as the resultant power dissipation.
Switch mode power supply basics

The basic concept behind a switch mode power supply or SMPS is the fact that the regulation is undertaken by using a switching regulator. This uses a series switching element that turns the current supply to a smoothing capacitor on an off.