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How Laptop Power Supply Works (Explained in Details)

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Power supplies on Desktop computers, Laptops, and other electronics serve the same function: converting Alternating Current into Direct Current and voltage regulation.

On Desktops, power supplies are a fundamental component you have to purchase and install while setting up. While on Laptops, they are external and incorporated into your Laptop charger/ Power brick. The power supply routes power to the motherboard, which then distributes it to the other components in your computer (display, CPU, battery, etc.)

What’s inside your Laptop Power Supply

Laptop Power supplies contain tons of electrical components like Metal Oxide Varistors, Capacitors, and Opto-isolators, but you only need to know/ understand four main components:

  1. Transformer
  2. Filter
  3. Rectifier
  4. Regulator

These four main components are responsible for the primary functions of the adapter.


The Transformer changes the incoming voltage to the recommended voltage level for your laptop. AC or Alternating Current flows at specific voltage ranges (100-240), and depending on where you are in the world; the Transformer will be responsible for stepping up or down the voltage flowing through.


The Rectifier changes the incoming charge from Alternating Current to Direct Current so that your computer can use it.


A filter smoothes out the waves after the conversion from Alternating Current to Direct Current. The waves don’t completely disappear to nothing, but rectifiers help even them out considerably. The DC, at this point, will still be unregulated.


The regulator regulates the output DC voltage, ensuring it maintains a leveled output regardless of changes in load. Essentially, it will protect your laptop from sustaining damage if an unexpected surge or dip occurs. 

AC and DC: How it works with your Power Supply

Alternating Current is one of the two major ways an electric current can flow, and it is characterized by a constant change in direction. The electric current flows forward and backward sporadically, and it is the most common type of electrical current you’ll find in office buildings, homes, and businesses.

In academia, it’s represented by a waveform called the sine wave, and the curve lines that make up the sign denote the electric cycle AC naturally makes. AC is measured in cycles per second or Hertz or Hz for short. AC is perfect for transferring electric current over large distances and is used by Powerhouses and companies.

AC and DC: How it works with your Power Supply

Direct Current 

Direct current flows in one direction, unlike Alternating current, and maintains a fairly stable voltage. DC is mostly used to power appliances and charge batteries because they are stable, and it’s the power most Laptop power supplies and electronics rely on to power their components. 

If the voltage, current, or polarity is wrong, your laptop and the adapter might underperform and, in the worst case, burn out and damage essential components like your battery, motherboard, or the adapter itself.   

How to find the Right Power Supply/ AC Adapter for your laptop

If you’ve recently misplaced your Laptop charger, or it stopped working for one reason or another, you’ll need a fresh new charger from your Laptop manufacturer or a third-party provider.

The easiest way to find the perfect specifications for your computer is by consulting the label on the back of the charger. It comes with all of the essential information you need to know about your charger and laptop power requirement and should take all of the guesswork out of the shopping process. 

Here is the most important information you’ll find on the back:

  1. Watt 
  2. Voltage 
  3. Ampere 

The Watt and Voltage requirement should meet the numbers put out by the Laptop manufacturers. The appropriate voltage guarantees that it can process power from the local DC power outlet, and Watts is the unit of power used to calculate electric energy in most electronics— including Laptops. Laptops that have high Wattages have intense power requirements and usually require a larger power Brick/ Adapter. 

Ampere is the rate of electron flow (or strength of flow) in an electrical conductor and the standard measurement of the strength of an AC Adapter or charger. A change in Ampere can reduce a day’s worth of trickle charging into a few minutes. 

The Pin Connector should match

When shopping for AC adapters, especially with third-party manufacturers, finding the perfect size could be a nightmare. There are over 10 different types of Pin connectors, and unless you have your former charger on-hand or information about your laptop, you’re likely to choose the wrong size of the connector. 

If you have issues researching and finding out more about your PC, we recommend googling the current specifications of your power adapter. Finding third-party manufacturers that line up with your current Laptop adapter requirement should be easier. However, if you’re still having a hard time finding the charger you need, talk to the attendant at whatever company/brand you wish to buy from. They should save you tons of time and money searching. 


Will using a third-party charger void your manufacturer’s warranty?

No. It should not, provided the specifications are similar enough.

Is a Universal Charger better than a new or used charger from my laptop manufacturer?

That depends on the kind of connector your laptop uses for charging. If it has a USB C charging port, a regular circuit, or a pin mouth charger, any universal charger will suffice, provided they meet the power requirement. If you use a special connector like Lenovo or Apple, you’re better off shopping for used or new markets.


In this post, we went into detail about Power supplies, how Laptop power supplies work, and how to shop for an AC Adapter for your laptop. At the end of this post, you should have a very solid idea/approach on how to find the right adapter for your PC the next time it breaks down as well as your options when you’re shopping. As always, we recommend doing more research before committing to any one product and knowing that the manufacturer’s adapter will always be the most compatible option for you. 

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Pigtou Editorial Team

A group of tech enthusiasts who find pleasure in troubleshooting and resolving various issues. When we're not engaged in writing, we typically enjoy playing table football or spending time with our office dog.
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