Switched mode power adapters are a type of mechanical device that transfers an electrical charge from a power source, such as a wall outlet, to a device, such as a personal computer, using a complex process that minimizes wasted energy. The power switches alternate between various states to use electricity efficiently and allow the device to function in various regions and power conditions.
Standard power supply units, commonly known as linear power supplies, accept an electrical current from a power source and regulate the output through a single transistor, which causes some of the charge to dissipate without being used and requires greater amounts of space. In contrast, a switched mode power supply utilizes a process wherein it alternates between three different states to convert the charge into the appropriate power usage for the device, drawing the current as necessary and avoiding dissipation.
As the power supply switches between the low usage, on and off states, it cycles the power more efficiently rather than simply discarding the unused amounts. This type of power supply is common in computers, as it is smaller in size and weight, and because it allows the machine to operate more efficiently for longer periods of time. Another advantage of these systems is that they are able to more easily use power supplies in different countries without risk of overloading. However, the systems include a more complex construction that sometimes leads to excessive noise or poor performance in low-end models.