Switching mode power supplies (or SMPs) are becoming common and in most cases have replaced traditional linear AC-DC power supplies to reduce power consumption, reduce heat dissipation, as well as size and weight. Switch-mode power supplies can now be found in most PCs, power amplifiers, televisions, DC motor drivers, etc. Almost any power source that requires a high efficiency power supply can be used as a switch mode power supply, which is becoming a more mature technology. By definition, a switching mode power supply (SMPS) is a power supply that uses semiconductor switching technology to provide the desired output voltage instead of the standard linear approach. The basic switching converter includes a power switching stage and a control circuit. The power switch stage performs a power conversion from the circuit's input voltage, V IN, to its output voltage, V OUT, which includes output filtering. The main advantage of a switching mode power supply over a standard linear regulator is its higher efficiency, which is achieved by internally switching transistors (or power MOSFET) between the "ON" (saturated) and "OFF" states (cutoff), both of which produce lower power consumption. This means that when the switching transistor is fully "on" and conducting current, the voltage drop on it is at its minimum, and when the transistor is fully "off", no current flows through it. The transistor, therefore, is like an ideal switch.
