Draw and explain the block diagram of SMPS.

Ans:

Circuit diagram:

Control Circuit:

Working: 

•  SMPS converts unregulated AC or DC voltage into a regulated voltage. In case of AC it is first converted into unregulated DC. This is fed to a high frequency step-up chopper which switches ON and OFF according to the variations.  

•  It uses a high frequency AC conversion stage to facilitate the use of a high frequency transformer for voltage scaling and isolation. The output of transformer is then rectified and filtered, to get a regulated output.  

•  Regulated output voltage is then given to the control circuit, which is a feedback circuit. The final output is obtained by controlling the chopping frequency according to the feedback signal.  

•  An output sensor senses the signal and connects it to the control unit. A reference voltage is given as one input along with the signal to the error amplifier, whose output helps to decide whether to increase or decrease the chopping frequency.