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

b.Buck  converter

c.Boost  converter

d.Buck boost converter