What is Switched-Mode Power Supply (SMPS)

Horace He

Last Updated: December 26, 2023

What is Switched-Mode Power Supply (SMPS)

An SMPS, which stands for Switched-Mode Power Supply, is a type of power supply commonly used in the lighting industry. It is designed to efficiently convert electrical power from one form to another using switching devices like transistors or MOSFETs. Unlike traditional linear power supplies, an SMPS operates at high frequencies, allowing for greater power conversion efficiency and reducing the size and weight of the power supply.

The operation of an SMPS involves several stages:

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  • In the first stage, the incoming AC power is rectified and filtered to produce a DC signal. This is achieved using a rectifier and filtration components, converting the AC power into a usable DC form.
  • The second stage of an SMPS involves high-frequency switching, where a high-frequency switch processes the DC signal, creating a high-frequency pulsating DC signal. This high-frequency operation enables efficient power conversion and further contributes to the compact size and weight of the power supply.
  • The third stage of an SMPS includes a power transformer. The high-voltage DC signal is stepped down to a DC signal of the appropriate level. The transformer plays a crucial role in voltage conversion and isolation, ensuring the output voltage matches the desired level.
  • In the fourth stage, the stepped-down DC signal is rectified and filtered to achieve a steady and constant DC output. This stage is essential for maintaining a stable output voltage, free from fluctuations or noise.
  • The final stage of an SMPS is the control circuitry. This circuitry monitors the output voltage and adjusts the high-frequency switch dynamically to maintain a continuous output stream of the desired voltage. The control circuitry is responsible for regulating the output voltage and keeping it within the specified range.

Frequently Asked Questions

What Does the SMPS Do

Like other types of power supply, an SMPS power supply transfers power from an AC outlet to a DC device. However, what distinguishes the SMPS is its capability to regulate the output voltage. It has the ability to adjust the output voltage to ensure a consistent output, regardless of any fluctuations in the load.

What Does SMPS Mean in Electrical

Switched-mode power supplies (SMPS), also known as switch mode power supplies, are widely used in electrical systems for efficient power conversion. They take an AC input from the mains voltage and convert it to a low voltage DC output.

What Are the Two Types of SMPS

SMPS can be categorized into two types, which are non-isolated converters and isolated converters, based on their circuit topology.

Is SMPS a AC DC Converter

In general, an SMPS functions by converting the AC source voltage into a DC voltage through a rectifier and an input filter. Afterward, a chopper is used to “chop up” the DC voltage, resulting in a series of square-wave high-frequency pulses (ranging from 20 kHz to 10 MHz) at the input of the transformer primary winding.

Is SMPS Necessary

The primary purpose of a Switched Mode Power Supply (SMPS) is to convert unregulated AC or DC voltage into regulated DC voltage that is suitable for electronic devices such as computers. This conversion is necessary because computers and other electronic items require a stable and efficient power supply.

Why Does SMPS Damage

Dirt and foreign substances, such as cigarette smoke and house dust, can cause damage to an SMPS. Additionally, overheating and ventilation failures are common reasons for SMPS failure. To prevent this, it is important to ensure that the ventilation is clear of dust and clutter. It is also advisable to avoid keeping the CPU in an enclosed desk.

How Do I Check My SMPS Power Supply

While voltage measurement can be done easily with the help of an isolation transformer, a more effective method is to utilize a differential probe for high-voltage measurements. Differential probes are equipped with two inputs and are specifically designed to measure the voltage difference between these inputs.

How Is SMPS Different From Normal Power Supply

An SMPS distinguishes itself from a linear power supply by its method of converting the primary AC voltage into the output DC voltage. Instead of relying on a linear approach, the SMPS employs a power transistor to generate a high-frequency voltage that is subsequently passed through a compact transformer and filtered to eliminate any AC noise.

Which Device Is Used in SMPS

In SMPS, the inverter utilizes the PWM technique. The inverter’s output is then converted to dc through the use of a diode rectifier. Since the inverter operates at a high frequency, the ripples on the dc output voltage can be easily filtered out using small filter components.

Which Switch Is Used in SMPS

Like other power supplies, an SMPS transfers power from a DC or AC source (often mains power), to DC loads, such as a personal computer, while converting voltage and current characteristics. It utilizes a high-frequency switching converter that converts DC to DC.

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