Switched Mode Power Supply (SMPS)
Switching mode power supply converts an unregulated DC voltage to a regulated DC output voltage . SMPS stands for switched mode power supply. A switched mode power supply is a power supply that provides the use of switches that are in one of two states, ON of OFF. In such a device power handling electronic components are continuously switching ON or OFF with high frequency in order to provide the transfer of electric energy via energy storage components. The advantage of switched mode power supply is that the switch dissipates very little power in either of these two and power conversion can be accomplished with minimum power loss and high efficiency. Because of the critical nature of power supplies in all equipment this approach improves both performance and reliability of the total system at no additional cost.
A switch mode power supply circuit is versatile. It can be used to produce multiple dc outputs using a circuit such as the fly back converter to step down an unregulated dc input voltage to produce a regulated c output voltage using a circuit known as buck converter or step down SMPS to step up an unregulated dc input voltage to produce a regulated dc output voltage suing a circuit known as boost converter or step up SMPS, to step up or step done an invert the input dc voltage and to switch mode power supply is a widely used circuit nowadays and it is used in as system such as a computer television receiver battery charger etc. The switching frequency is usually above 20KHz so that the noise produced by it is above the audio range. It is also used to provide a variable dc voltage to armature of a dc motor in a variable speed drive. It is used in a high frequency unity power factor circuit.
This types of regulator can be classified into PWM switch mode ( square mode ) and resonant switch mode ( sine wave).
There are four basic topologies of PWM switch mode regulators or converters .
a.Fly back converter
d.Buck boost converter