Different Types Of Switched Mode Power Supply (SMPS)

Last Updated on October 10, 2024

Switched-Mode Power Supplies are the vital components of modern electronic systems and applications primarily used to convert electrical power more efficiently and reliably. While regular linear power supplies convert pure waves of electrical energy into others, the SMPS makes it by switching the input on and off at a high frequency. That is one of the essential peculiarities of such conversion, which helps to reduce the energy lost and get the final product of a smaller form factor. The following article will explore the topic of SMPS, discussing its types, applications, advantages, and key characteristics. The SMPS’s main task is to switch on and off as quickly as possible. The final conversion frequency usually varies from 20 kHz to 1 MHz.

What are the Major Types of SMPS?

Several SMPS are designed for specific applications and operating principles. The four major types are:

• AC to DC Converter (Off-Line Converter)
• DC to DC Converter
• Flyback Converter
• Forward Converter

Let’s explore each of these in detail.

1. AC to DC Converter (Off-Line Converter)

The AC-to-DC converter unit is the most common application of Switched-Mode Power Supply (SMPS) techniques. It is used in various applications, from small domestic electronics to the largest industrial installations. This converter transforms an AC input into a regulated DC output.

• Rectification: It turns the AC input into unregulated DC (also called raw power).
• Switching: The chopped high-frequency AC load of the DC is transformed by a circuit with faster transistor switches in it.
• Transformation: it adjusts the voltage level.
• Rectification and Filtering: it converts the high-frequency AC back to DC and smooths it for the final output.

Applications: Power supplies for computers, televisions, battery chargers, and industrial control systems.

Advantages: High efficiency, wide input voltage range, compact design.

2. DC to DC Converter

DC-to-DC converters usually find applications in devices that use batteries for functioning. One uses them when they require a stable DC output from DC input.  The main types include:

• Buck Converter (Step-Down Converter): These help reduce the input voltage to a lower output voltage.
• Boost Converter (Step-Up Converter): These help increase the input voltage to a higher output voltage.
• Buck-Boost Converter: Depending on the requirement, Buck-boost converters step up or step down the voltage. 

Applications: Mobile phones, laptops, power banks, automotive systems.

Advantages: Versatile, efficient, compact.

3. Flyback Converter

The flyback converter is an isolated SMPS frequently used in low-power applications. When it is in the “on” phase, energy is stored in a transformer and released when it is in the “off” phase. After that, the energy is transformed into the required output voltage.

Key Characteristics:

• Design: For low-power applications, it is economical and straightforward.

Applications: Television, monitor, and other consumer electronics power supply.

Benefits: Low cost, easy-to-use design, appropriate for low-power uses.

4. Forward Converter

The forward converter is another type of isolated SMPS, but unlike the flyback converter, it transfers energy directly to the output during the “on” phase. This type of converter is suitable for medium to high-power applications.

Key Characteristics:

• Energy Transfer: Continuous energy transfer to the output.
• Complexity: More components compared to flyback converters, including additional windings and components to reset the transformer core.

Applications: Industrial power supplies, telecommunications, high-power consumer electronics.

Advantages: Higher efficiency, suitable for higher power levels.

Comparison of SMPS Types

The following table summarises the key features of the major types of SMPS:

What are the Advantages of SMPS?

SMPS are preferred over traditional linear power supplies for several reasons:

• High Efficiency: SMPS have high-efficiency levels(80%-90%), reducing any loss in energy.
• Compact Size: High-frequency switching gives way to smaller components, resulting in a compact size.
• Wide Input Range: SMPS can handle a wide range of input voltages, making them perfect for global applications.
• Flexibility: SMPS can provide multiple output voltages from a single input, contributing to different needs.
• Less Heat Generation: SMPS are highly efficient & generate less heat.

What are the Drawbacks of SMPS?

SMPS have many disadvantages despite their benefits:

• Complexity: The design of SMPS power supplies is more intricate than that of linear power supplies, necessitating close attention to noise and electromagnetic interference (EMI).

• Cost: Advanced features and improved efficiency frequently have a higher starting cost.
• EMI Issues: With a high generation of electromagnetic interference, additional protection is required.  

Conclusion:

SMPS has entirely changed the process of power conversion in modern electronics. They are flexible, come with compact designs and are highly efficient. They find applications with many engineers and designers who can select from various types of SMPS available in the market. They have become a go-to source for providing power to electronic devices. You will find all the major SMPS at competitive prices in Industrybuying.