SMPS: Full Form, Types, Benefits, Advantages, Disadvantages

smps full form

SMPS Full Form

SMPS, short, for Switched Mode Power Supply, uses components like capacitors, inductors, and semiconductors such as diodes. It is employed for power conversion and facilitates the alteration of one DC voltage level to another. Similar to power supplies SMPS adjusts the voltage and current characteristics while transferring power from a DC or AC source to DC loads like a computer. Switching regulators are preferred over regulators when there is a need, for efficiency, smaller size, or lighter weight. Common applications of SMPS include power adapters, desktop computers, and server management.

What is a switch-mode power supply (SMPS)?

A switching regulator is a component, in a power supply called a switched mode power supply (SMPS). Its purpose is to convert power. An SMPS adjusts voltage and current to provide power to DC devices from either a DC or AC source like power supplies do.

What is the full form of SMPS?

Switched Mode Power Supply, commonly known as SMPS has circuit designs each offering features and benefits that dictate the transfer of input power, to the output. The transformer is a component in circuit designs such as flyback, push-pull, half-bridge, and full-bridge configurations providing functions, like isolation, voltage regulation, and generating multiple output voltages. In isolated versions, power conversion takes place through inductive energy transfer instead of relying on a transformer.

Types of SMPS

These power supplies are, among the most used and popular options, for everyday users.

Changing DC to DC

The electricity sourced from the wall outlet undergoes a conversion process, from AC to high-voltage DC. Following this conversion, the DC power is fine-tuned and channeled through a transformer to reduce its voltage. Once this power has been transformed it undergoes another round of filtering before being utilized as the output.

Converting Ahead

In a converter, the coil consistently carries current, irrespective of the transistor’s state. When the transistor is inactive a diode conducts to maintain energy flow, to the load. In the phase power is supplied to the load with some power being stored in the coil.

The Flyback Converter

In a converter, the inductor holds energy within its field while the switch is turned on. This energy is then discharged into the output circuit when the switch is off. The output voltage of a converter is determined by its duty cycle.

The Flyback converter with self-oscillation

According to the Flyback theory, there is a rise, in passing through the primary transformer while conducting following a slope of Vin/Lp. The fast recovery rectifier works in bias to maintain transistor conduction by utilizing voltage in the secondary and feedback windings. As the peaks the core saturates, leading to challenges for the input windings, with sudden current surges and triggering the switch to exit saturation.

[Also Read: What is the full form of MD? Advantages of MD specializations]

What is the Working Principle of SMPS?

It works by using a semiconductor switch, such, as a MOSFET to control the supply voltage by turning it on and off at a rate thus managing the output voltage. This output voltage changes accordingly when the switching frequency is adjusted. Like power supplies, an SMPS (Switched Mode Power Supply) transfers electricity from a source ( an AC outlet) to a DC device. What makes SMPS unique is its capability to regulate the output voltage ensuring an output regardless of load fluctuations. Unlike regulators that can only reduce voltage, SMPS has the advantage of being able to both increase and decrease it.

Working of AC-DC Converter SMPS

In this kind of SMPS, the initial power is, in AC form. Gets changed to DC at the end. Rectifiers and filters help turn AC into DC. The varying DC voltage is utilized to adjust the power factor in circuits impacted by a pulse close to the voltage peak, in the rectifier.

Working of DC-DC Converter SMPS 

This energy source derives its power from a DC power source providing high-voltage DC. The DC voltage is subsequently transformed into a frequency ranging from 15KHz to 5KHz. Through a step-down transformer, it is lowered to 50 Hz. The rectifier receives the transformer output supplying power to the loads. An oscillator timing control system manages the timing, in a closed-loop manner. The transformer functions effectively with a duty cycle of 50%. Decreasing the duty cycle reduces both the transformer’s power consumption and interruptions, in operation.

Fly-Back Converter Type SMPS Working

A flyback converter SMPS is a power supply that delivers more than 100 watts of output power. The circuit design, for these power supplies is simple and less intricate compared to types. The primary objective of power supplies is to minimize power consumption. By utilizing a MOSFET the unregulated input voltage switches, at a frequency of 100 kHz to achieve the desired output voltage. A transformer isolates voltages. In a fly-back converter, PWM controls the switch. Unlike transformers, the fly-back transformer exhibits characteristics with its two windings functioning as magnetically coupled inductors. Capacitors and diodes are incorporated to improve the filtering of the transformer’s output signal.

Forward Converter Type SMPS Working

This SMPS variant shares a design akin, to the SMS converter. In managing this SMPS the switch links to the winding that feeds power to the transformer output. The filtering and correction circuitry in this setup are more intricate when contrasted with a converter. Such SMPS units, commonly referred to as DC-DC buck converters find utility, in scenarios necessitating transformer isolation and voltage adjustment.

Limitations of SMPS

The following are the limitations of SMPS:

  • SMPS can be quite complex.
  • SMPS often exhibits fluctuations. Lacks precise regulation.
  • It functions solely as a step-down regulator.
  • SMPS provides only a single voltage output.
  • High ripple affects control performance in SMPS.

How does a switch-mode power supply (SMPS) operate?

An SMPS typically consists of four phases; rectification, filtration, switching, and regulation. Let me break down each stage for you in an understanding way;

Rectification: The AC power input changes to DC using a rectifier, which can be a full-wave bridge or a half-wave rectifier. This device allows electricity to move in one direction resulting in fluctuating DC voltage.

Filtration: After rectifying the pulsating DC voltage, it passes through a filter—a capacitor—to smooth out the output signal. This capacitor helps reduce fluctuations and disturbances guaranteeing a DC voltage.

Switching: The filtered DC voltage enters a switching circuit typically made up of a high-frequency oscillator and either a power transistor or MOSFET. The oscillator generates pulses at a frequency directing the power transistor to rapidly turn on and off.

Transformation: The changed voltage passes through a transformer, adjusting it higher or lower as needed for the desired outcome. A control circuit supervises the result adjusting the frequency of switching and duty cycle to maintain a voltage level.

Advantages and Disadvantages of SMPS

Advantages of SMPS Full Form include:

  • The switch mode power supply is very light in weight.
  • In a switched mode power supply (SMPS) the output stays consistent and reliable when the input voltage fluctuates.
  • SMPS operates with efficiency ranging from 68% to 90%.
  • It is very compact and powerful.

Disadvantages of SMPS include:

  • Its circuit design is quite intricate.
  • An SMPS produces electrical noise.
  • A full-form SMPS is pricier compared to a linear supply.

Uses of SMPS

Switching Mode Power Supplies (SMPSs) find extensive applications across various industries such as servers, computers, and power plants. They play a role in vehicles (EVs) and hybrid vehicles for battery charging as well as, in railway systems. Other uses include lighting and the machine tool sectors.


Switched Mode Power Supply (SMPS) is a technology that effectively transforms power to cater to devices. It comes in forms such, as DC-DC, and flyback converters. The advantages of SMPS are its efficiency, lightweight construction, and compact design. Although SMPS systems offer advantages, they can be complex, cause disturbances, and are generally more expensive than linear power supplies.