SMPS Block Diagram | Switched Mode Power Supply

Hey, today we are going to see and understand the SMPS Block Diagram. You can easily understand the total working principle of SMPS from the block diagram of SMPS or Switched Mode Power Supply. Here we will discuss the working principle of an SMPS circuit.

SMPS is nothing but an electronic circuit that is used in most of the electronic devices to provide their required voltage and current. We know that electronic circuits and devices are very sensitive. Most of the electronic devices work on a DC power supply. An electronic circuit may contain different components and they required different voltage and current. So the main purpose of the use of SMPS is to provide the required voltage and current for each component.

SMPS is used in computers. So there are many components and circuits inside the computer. All of them do not take the same voltage and current. In this case, the SMPS provides different voltages and currents to different components and circuits according to their requirement.

Block Diagram of SMPS

Here you can see the SMPS block diagram. It is an AC to DC Buck Converter or Step Down SMPS. That means it takes high-voltage AC as input and low-voltage DC as Output.

As per the above block diagram, an SMPS has the main following parts,

1. High Voltage Input Rectifier Circuit
2. High Voltage DC Filter Circuit
3. High-Frequency Power Semiconductor Switch
4. Step Down Flyback Transformer
5. Low Voltage Rectifier Circuit
6. Low Voltage DC Filter Circuit
7. Control Circuit
8. Pulse Signal Generator
9. Error Detector
10. Opto isolator

Switched Mode Power Supply Working Principle

According to the above block diagram, the working principle is explained below.

1. The first block is the Bridge rectifier circuit. So the input high voltage AC supply(230V) is given to the rectifier and it is converted into high voltage DC(230V).

2. Then the unfiltered DC is filtered by the filter circuit. 

3. Then the high voltage DC is converted into very high-frequency square wave AC. Here the high-frequency switch is used to convert DC to AC. The switch is controlled by the feedback and control circuit.

4.The high-frequency AC is step down into low voltage( maybe 12V, 6V, etc) by a flyback high-frequency transformer.

5. Then again a low-voltage rectifier circuit is used to convert the low-voltage AC to DC.

6. A DC filter circuit is used to filter the low voltage unfiltered DC into pure DC.

The feedback path and control circuits are used to control the output DC supply. Mainly the Pulse Width Modulation Circuit is used for the control circuit.

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