CompTIA A+ Prep: Different Types of Power Supplies and How They Work


CompTIA A+ Prep: Different Types of Power Supplies and How They Work

A power supply device provides electricity to operate electronic devices. A power supply would have considerably different ways by which it supplies electricity to devices. It is basic knowledge and fundamental if one is learning about how power supplies are attributed to computers. Individuals seeking CompTIA A+ Certification Training would require understanding how a power supply works and what the basic functionalities of different sources of power are. This article would comprehensively cover the different sources and their incorporation in modern computer systems.

The basic function of every power supply device is to convert AC or Alternative Current-voltage to DC or Direct Current voltage, which is needed by electronic devices in order to be powered. A normal power supply has four major models and each one has a particular function, which is explained below:

  • Transformer – The first module that is responsible for converting high voltage AC or Alternative Current to low voltage DC or Direct Current.
  • Rectifier – Rectifier converts low voltage Alternative Current or AC to Direct Current or DC.
  • Smoothing – The DC provided by Rectifier can be different, so a Smoothing simply reduces this varying current into ripples.
  • Regulator – A regulator sets the DC voltage to a fixed value by taking apart the ripples.

The four primary types of power supplies

Linear Regulated Power Supplies:

It’s the basic type of power supply that regulates output voltage by decreasing the input voltage. It depends on the variable connectivity of an electronic device, in order to do this. Therefore, a considerable amount of power is a loss in the form of heat. These supplies work by converting AC input to regulated DC output. A circuit that is used in this case has two range, one that allows more voltage at a lower current and the other that allows more current at a lower voltage. It has two basic types – shunt regulators and series regulators. Shunt regulated power supply is not efficient, while, a Series regulated power supply is more common and it is actually a product of voltage drop and output current. Linear regulated power supplies are simple and mostly used in industries. Their systems give off low noise and are much cost-effective. They are mostly used in ground-based systems.

Switching Mode Power Supply or SMPS:

This one operates in an ON and OFF mode. SMPS uses switching circuits, inductors, and capacitors to get a regulated output voltage. A Switching Mode Power Supply is considered to be highly efficient because it does not allow for energy loss. Its application is rather simple, and it is light in weight. Its light weight comes from the removal of a heavy and low-frequency transformer. It is more often used in domestic products.

Programmable Power Supply:

A Programmable Power Supply provides electricity through a computer interface and relies on both Switch Mode and Linear Regulated systems to produce power. It consists of a current, microcontroller, analog circuits, analog to digital converters, LCD display, keypad, and the serial peripheral interface. The required voltage is entered as a number via the keypad to the microcontroller. In return, the microcontroller converts the analog voltage from one source to digital via the analog to digital converter. Then, the serial peripheral interface regulates the digital voltage to match that of the input number entered to the microcontroller. This option has a significant advantage that accurate measurement of voltage can be regulated which was impossible to achieve with switch mode or the linear regulated system. The programmable power supply is mainly used in ultra-sonic vibration measurement tools.

Uninterruptible Power Supply (UPS)

It is a modern type of power supply device that is prominently used as a backup measure in case of power loss. Devices can crash immediately if there is a sudden power outage. So, in order to prevent that, UPS is used. It has three main categories; namely Standby, Online, and Line-interactive.


The first category provides protection and backs up of up to 20 minutes of time frame. A Standby UPS turns on when there is a loss in power under the threshold. This power can last up to 20 minutes.


The second category of UPS uses a single power converter in order to provide with power. The line-interactive UPS is popular in the IT landscape around the world and it is usually more durable and cost-effective to set up. It provides power backup for up to 5 to 30 minutes.


The third category of UPS is a blend between Line-interactive and Standby. It provides backup for up to 5 to 30 minutes. It also maintains a firewall between incoming power and the electronic equipment that is sensitive. Its main purpose is to protect electronic devices from crashing down when there is an uninterrupted power cut. Apart from that, some UPS are also able to correct common power issues such as voltage fluctuations, noises, and loss of input voltage. They also serve to protect devices such as computers, data centers, and telecom equipment from crashing down when an abrupt power cut occurs. Besides, these UPS also function particularly for certain kind of devices which are very sensitive to fluctuations in power.

Various power sources are used to supply systems with power efficiently whenever there is a cut or outage. In addition, modern workplaces have also integrated renewable energy resources including solar panels and wind power machines to generate electricity, store, and be utilized in industrial applications. If someone wishes to delve deeper into how further different power supply units escalate their functions, then they should take up CompTIA A+ classes at this respective platform. These classes are meant for every individual looking forward to acquiring specialized training and certification.

The concepts of power supply units are important not for just theoretical understanding but their key aspects prove to be useful in practical applications, which computer experts would surely encounter at different stages of their career. It is important to know these basics and indulge in some practice to further make one’s understanding concrete.

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