What is SMPS its functions and Types

What is SMPS and its functions – Complete information

In this article you will know what is SMPS? (What is SMPS) As we know Power Supply is very important for all electronic devices, because without it no system can be started. But one thing is to be understood here that all electronic devices do not require electric power in the same voltage.

If you give power supply in high voltage to electronic equipment like computer, then the chances of it getting damaged are high. SMPS is used to avoid these disadvantages, it is a type of electrical device. It is mostly used for power supply in PC, mobile, battery charger, TV and vehicles.

In this post you will get to read complete information about SMPS like what is SMPS and how does it work? What is its full name, how many types are there. So let’s first of all what is SMPS? Understand this very well, then we will talk about other aspects of it.

Topics

• What is SMPS? (What is SMPS)
• Major Functions of SMPS
• Main Types of Power Supply in Electrical Circuits
• Difference Between Alternating Current and Direct Current
• Types of SMPS
• Key Parts of Computer SMPS
• SMPS Connectors
• HOW SMPS WORKS
• Benefits of SMPS
• Conclusion

What is SMPS

Switched Mode Power Supply or “SMPS” is a type of power supply unit (PSU) that converts unregulated AC or DC voltage into regulated DC using switching devices. SMPS uses a switching regulator to convert one form of electricity to another.

For example, the electricity that comes to our homes is an alternating current (AC). But sensitive equipment like computer requires stable and efficient power supply. Therefore SMPS is used to provide power to various components of the PC, which converts AC into static energy. We call this direct current (DC).

SMPS is also called Switching Mode Power Supply. These electronic devices include a combination of diodes and MOSFETs such as inductors, capacitors and semiconductor devices. SMPS is used for power supply in almost all our home electronic devices.

SMPS is a piece of hardware in a computer, which is fitted inside the case like the back. If you open the computer, you will see a tin box in the backside. Its job in a computer is to provide usable power for its various parts such as RAM and motherboard. What are the main functions of SMPS, let us understand it in detail.

Major Functions of SMPS

Functions of SMPS:

• To turn on the electronic equipment, it works to supply power from source to load.
• SMPS converts a wall-voltage AC power to lower voltage DC power.
• Despite the variation in I/P voltage, it provides reliable output by regulating electric power.
• Different components inside the computer require different amounts of electric power. SMPS provides power to each part as per its requirement.

Main Types of Power Supply in Electrical Circuits

We already know how important power supply is for any electronic system. But it is not necessary that one type of power supply unit should be used to supply power to all electronic devices. Actually it cannot even be done because all the devices demand different voltage power. That is why power supply in electrical circuits is classified into different types.

Unregulated Power Supply

This type of power supply equipment does not have voltage regulators. They are made to produce specific voltage. These are a type of block wall charger, which converts AC into a small package of DC. But the output voltage provided by them is not constant. In this, AC is converted into DC with the combination of transformer, rectifier and filter.

However, due to its simplicity, it is the cheapest and most reliable for low power requirements. But due to not being able to give clean voltage, they are not used in most of the devices. It is also called linear power supply.

Regulated Power Supply

Voltage regulators are present in these, due to which the output voltage is always obtained clean. It has the ability to convert unregulated alternating current into stable direct current. Their main function is to provide a stable voltage to a device or circuit. This ensures that the voltage changes coming in the input do not affect the output. For this reason we get a constant constant voltage.

In this, AC is converted into pure DC with the help of step down transformer, bridge rectifier, DC filter and regulator. We also call it Switch Mode Power Supply. Regulated power supply is used in almost most electronic devices.

Difference Between Alternating Current and Direct Current

Both AC and DC describe the types of current flow in a circuit. In which the electric charge in alternating current (AC) changes direction from time to time. In the same direct current (DC), electric charge i.e. current flows in only one direction. The biggest difference between this is that AC has a frequency. For example, the electricity coming to our homes is AC, whose frequency is 50Hz.

There is no frequency in the same DC. AC can be transmitted over long distances, while DC cannot. Can not store AC, only can store DC in battery. AC is always in high voltage, but DC is low voltage.

Types of SMPS

The different types of SMPS include:

• DC to DC Converter
• DC to AC Converter
• Flyback Converter
• Forward Converter

1 DC-DC Converter

In this type of SMPS, high voltage DC is obtained from a DC power source. After this this DC power is usually switched in the range of 15KHz-5KHz. After this it is placed in a step-down transformer, which has a frequency of 50Hz. Now the output received from this transformer is further fed into the rectifier.

Now the rectified output power obtained is used as the load source for the electronic device. In this, using Puls Width Modulation, the switching power supply regulates the output. This switch is operated by the PWM oscillator. By doing this indirectly the step-down transformer automatically comes under control.

That’s why the output is controlled by PWM. Now because the output voltage and PWM signals are inversely proportional to each other. So when the duty cycle is high, the maximum power is passed through the transformer. On the contrary, if the duty cycle is less, then the power dissipation in the transformer is also less.

2 AC-DC Converter

In these SMPS, the main AC is converted into DC with the help of rectifier and filter. To do the switching process, MOSFET transistors are used in it. This transistor consumes low on-resistance, while can resist high current. In this, the frequency of switching is kept so that it is low for a normal human being.

PWM is also used in this to control the switching process. In this, the level of AC voltage is raised and fed into the transformer. Then the output received from the transformer is further rectified and smoothed by giving it to another rectifier and filter. In this, the o/p voltage is controlled by the feedback circuit by comparing it to the reference voltage.

3 Flyback Converter

This type of SMPS has very low output power. This is a very simple circuit as compared to the rest of the SMPS circuit. These are used for low power applications. Using a MOSFET, the unregulated i/p voltage is converted into the preferred o/p voltage with a continuous result. The switching frequency in this is about 100KHz.

4 Forward Converter

It is similar to a flyback converter. But, in this type of SMPS, other methods are used to control the switch. It is also called DC-DC buck converter. It consists of a transformer, which is used for scaling and isolation. In addition to the diode, capacitor, an inductor is also connected. If the switch is turned ON, then i/p is given to the primary winding of the transformer.

Key Parts of Computer SMPS

Some major parts and their functions present inside a computer SMPS:

Rectifier: This part converts AC power into DC, which we call diode.
Capacitor: Filters the unregulated DC converted by the rectifier and converts it into smooth DC.
Transformer: A transformer controls the incoming voltage by up and down.
Voltage Regulator: It controls the DC output, so that power, volts and watts can be given to the computer hardware in the right amount.
Hit Sink: Absorbs heat when the transistor is hot.
Fuse: It protects the circuit from heavy voltage.
Transistor: Its job is to switch the power.
Choke Coil: Works to smooth the received DC current.

By reading the above mentioned parts and their functions, you can understand the working of an SMPS very well. So let’s now know about its connectors. Because with their help we are able to supply power to different parts of the computer.

SMPS Connectors

Different types of cables or connectors are used to supply power to different components of the computer, the list of which is given below.

1) ATX 24 Pin Power Connector

From this connector power is supplied to your motherboard and all its connected components like RAM, onboard graphic card, PCI cards etc. It has a total of 24 pins (20 + 4), in which twenty pins are separate and four pins are separate. If you have an older motherboard, it will take twenty pins. But modern motherboards require 24 pin power connectors.

2) ATX P4 Power Connector

This connector supplies power to the CPU installed in the motherboard. The current given by it is 12V. Usually some motherboards have 4 pin sockets to supply power to the CPU and some have 8 pin sockets available. That’s why it comes in 8 pin (4+4).

3) SATA Power Connector

It is used to supply current to SATA devices such as Hard Disk, DVD ROM or Drives. These connectors supply 5V and 12V power.

4) PCI-E Express Power Connector

These connectors have 6 to 8 pins. These connectors supply power to the computer’s PCI-E Express devices such as the graphics card. These connectors supply 12V power.

HOW SMPS WORKS

Let us know how SMPS converts AC into DC and makes it usable for electronic devices. In this process, AC power is first inputted into SMPS with the help of wire. After which NTC, with the help of fuse, line filter and capacitor, stabilizes it a bit and gives it to the rectifier and filter. Rectifier and filter convert it from AC to DC.

The output DC current obtained in this step is given to the switching transistor. In which with the help of NPN transistor and switching cycle, the DC current is once again converted into a more clean AC current. Even the process takes place in the primary circuit of the SMPS.

After this this current is given to the rectifier and filter present in the second part of the circuit, which again converts the AC current into very pure DC current. By changing the current again and again, we get stable DC power. The rectifier and filter output are connected to the starter transformer and amplifier. This is where the wire comes out to power the electronic equipment.

Benefits of SMPS

Its biggest advantage is that SMPS gives stable current to all electronic devices as per their requirement. So that there should not be any defect in those equipment. The design of SMPS is quite simple and the size is also quite small, due to which it does not take up much space. No matter how many variations come in your input voltage, but SMPS ensures that the output voltage will be absolutely stable and regulated. An SMPS is cheap compared to other power supplies.

Conclusion

So hopefully, after reading this post till the end, you must have understood the concept of SMPS. This article What is SMPS (What is SMPS) is another post in our Computer Hardware series. If you want to get information about all the parts of the computer, then go to the Computer Part category of this website. If you have any question or suggestion related to this article, then please tell us in the comment below. Your suggestions are very valuable for us.

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