A Guide to AC/DC Adapters: Choose the Right One for Your Device

What's Inside

What is an AC Adapter?
Learn more about AC adapters, which are external power supplies that convert alternating current (AC) from a wall outlet to a direct current (DC) needed by an electronic device.
Check Electrical Ratings to Choose the Right AC Adapter for Your Device
Read more about the first steps you should take when deciding on an AC adapter.
Select an AC Adapter and Device with Matching Specs
Read more about how to determine which AC adapter will work best with your device.

What is an AC Adapter?

An AC adapter is an external power supply that converts alternating current (AC) from a wall outlet to a direct current (DC) needed by an electronic device. In this way, it is an AC/DC converter. When it supplies power to a battery-powered device, it is also accurate to describe it as a charger. Before picking the right AC adapter for your device, it is useful to know the reasons most portable electronics use external power adapters.

How Do AC Adapters Work?

Installing the power components of devices in external AC adapters allows manufacturers to make them smaller. Those researching how to choose the right AC adapter should know that devices with external power adapters are lighter than those with integrated AC adapters. Having a separate and external AC/DC power adapter also reduces the heat produced inside an electronic device. This design reduces electrical noise and improves safety as well.

A manufacturer can also support a wide voltage range by choosing an external power supply when designing the right AC adapter for your device. Finally, external power adapters are easier to replace. Users do not have to throw away their devices if voltage spikes, they experience brownouts or if electrical fires destroy their external power supply units.

What’s the Difference Between AC and DC Adapters?

The terms “AC adapter” and “DC adapter” are frequently used interchangeably, but they refer to two distinct types of adapters. AC adapters are used to convert from one voltage to another and are used to charge electronic devices. DC adapters convert alternating current into direct current and are typically used to connect devices to external power supplies.

AC Adapter Types

Different types of AC adapters are available and recommended for different purposes. Desktop adapters are larger than other types and are typically used for desktop computers and related peripherals, such as printers. Wall adapters are generally smaller than desktop adapters, plug directly into the wall and are typically used for laptops and related devices. Travel adapters are used to convert between the different shapes of outlets in different countries, and they are generally used for charging devices during international travel. There is a Type C adapter designed specifically for universal use throughout Europe. And there are some adapters specifically designed to protect against surges and short circuits.

DC Adapter Types

DC adapters also come in types that mount via wall outlets or are placed on a desktop. In addition, DIN adapters are specifically designed for industrial use to provide power to machinery and equipment. Open adapters are another type of DC adapter typically used in the manufacture of electronic equipment.

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Check Electrical Ratings to Choose the Right AC Adapter for Your Device

Before trying to find a matching AC adapter for a device, check if the OEM (original equipment manufacturer) adapter is available. Device manufacturers sometimes offer replacement chargers/adapters for their products. Determining how to choose the right power adapter for a device becomes easy if this OEM accessory is available. Find the specific adapter for the device by searching for it using the model number printed on the adapter shipped with the device.

In some cases, OEM adapters are no longer available from manufacturers. Therefore, finding the right AC adapter for your electronics requires selecting a compatible third-party accessory. The first step is to determine the electrical rating of the device.

When learning how to choose an AC adapter, it is also necessary to understand power adapter specifications. Manufacturers usually print such information on the labels of these power accessories. Alternatively, check the device’s user manual for the electrical ratings of its AC adapter. The most important sections to read on a power adapter label are voltage and current. However, polarity is also an important factor.

The unit for voltage is volt (V), while current ratings end in amps or ampere (A). Power adapters have AC inputs and DC outputs. Depending on the region, AC input can be 110/120V or 220/240V. To make it easier for users to choose an AC adapter, manufacturers usually offer adapters that support both voltages. Dual voltage adapters have listed input AC voltage ranges of 110 - 220VAC or 100 - 240VAC. These are most useful for travelers researching how to choose the right power adapter that will work in other parts of the world. The DC voltage (VDC) of the power accessory is as important as its AC voltage (VAC). When reading an adapter label, the VDC will be under the DC symbol.

The AC symbol is a wave, while the DC symbol is a solid dash with three short dashes underneath it. The DC voltage is the output voltage of the adapter, and it is usually much lower than the input AC voltage.

Choosing the Right AC Adapter for Your Device (With Specs to Match)

The right AC adapter for your device is one with matching electrical ratings. The device’s input voltage and current must match the adapter’s output voltage and current. Check the device’s product label or user manual to see its rated voltage and current. Shoppers learning how to choose AC adapter should know that most power adapters have output DC voltages below 20V while their input AC voltages are over 100V.

Matching the Voltage

Choosing an adapter with a higher or lower voltage or current rating may cause the connected device to malfunction. This happens if the adapter’s VDC is lower than the device’s input voltage even when their current ratings are the same. Using an adapter with a higher voltage will cause the connected device to detect an overvoltage. An AC adapter supplying electricity at a higher voltage than required will cause the connected device to run hotter. Sending power at a higher voltage will also shorten the lifespan of the device and may fry its internal circuits.

Matching the Current Rating

Using an AC adapter with a different current rating can be an issue. When considering how to choose an AC adapter, avoid picking one that delivers a lower current than required by the device. Even when both the adapter and the device have the same voltage rating, the device will attempt to draw more current than the AC adapter can manage. This can cause the adapter to overheat. The device may fail to power on or struggle to stay on. If the current is too low, the electronic device may stay on, but its battery will not charge.

It may surprise you that you can use adapters with higher current ratings than your devices. This recommendation holds true, as long as both devices have the same voltage rating. For example, a 10V/8A adapter can safely power a 10V/5A device.

Matching the Polarity

The last thing to consider when researching how to choose the right power adapter is polarity. The polarity of the AC adapter’s connector must match that of the power input or charging port on the device. There are two types of connector polarities: center positive and center negative. It is worth noting in an AC adapter buying guide that most power adapters use center-positive connectors.

A center-positive connector in the AC adapter has a tip that has a positive polarity. Its barrel or ring has negative polarity. A center negative connector has the opposite arrangement. It is essential to differentiate the symbols for both types of connectors when learning how to choose the right AC adapter for your device. Manufacturers may denote polarity by putting + (positive) and - (negative) signs in front of voltage ratings. Alternatively, they may represent polarity with diagrams. When researching how to choose an AC adapter, remember that a polarity diagram of the adopter features a circle on both sides. A center-positive adapter polarity has a line extending from a positive circle to the open-end circle.

It's also important to find a power adapter with a connector that fits into the input power port of the connected device. If the connector is too wide, it will not slide into the power port, and if it's too narrow, it will form a loose fit and may fall out during use.

To choose the right AC adapter for your device, find one with voltage and current ratings that match those of the device. Durable monitor cables are convenient for visual artists who need proper video display, and the cable is a part of the equation. Do not forget to also consider the polarity and size of the adapter’s connector as they must be compatible with the device’s power input port. A quick read of this AC adapter buying guide will help you choose the right AC unit from the selection of AC/DC external power adapters.

For Laptops

The most important consideration for a laptop charger is to ensure the voltage and current specifications match those of the laptop. It’s also important to check the power distribution requirements of the laptop.

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For Desktops

For desktop computers, experts recommend a high-quality ATX power supply unit. This type of adapter is specifically designed for desktop computers and components. As with laptops, users should be sure to use an adapter with the same wattage as the desktop.

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For Gaming

Many brands produce AC adapters that are appropriate for gaming consoles and devices. As with other electronics, the adapter should match the wattage of the devices. It’s also necessary to make sure the adapter has the right type of connector for the gaming device.

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For TVs

As with gaming devices, check the voltage and amperage specifications, as well as the connector type, to ensure proper power delivery. Most TVs manufactured in recent years use power cords with a C13 connector.

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For Networking

As with gaming devices, check the voltage and amperage specifications, as well as the connector type, to ensure proper power delivery. Most TVs manufactured in recent years use power cords with a C13 connector.

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For Home Appliances

As with every other type of use case, the key factor in choosing an AC adapter for home appliances is making sure the electrical ratings match. For home appliances, the best source of information is usually the label on the appliance itself, which will provide the correct output voltage and amperage.

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Frequently Asked Questions About AC Adapters

Power adapters are used to convert the voltage of a device and can help to prevent damage to the device or blowing a fuse. Travel adapters are typically used when traveling internationally, because different countries use electrical outlets of different shapes. A travel adapter can allow a device to be plugged into an outlet by changing the shape of the plug to fit the shape required by the country or region.

Most power adapters have an efficiency rating between 80% and 90%, but some high-quality adapters can reach ratings as high as 95%.

Because many adapters contain hazardous materials and are not recyclable, they can contribute to environmental pollution. However, there are several adapters on the market that are more environmentally friendly options. And when adapters are deemed less eco-friendly, it’s important to consider responsible methods of disposal.

To safely clean an AC adapter, the first step is always to unplug it from the power source. When cleaning, avoid using liquids. For removing dust and other light debris, a dry cloth is recommended. For adapters that require more rigorous cleaning, consider a cloth dampened with rubbing alcohol, compressed air, toothpicks or cotton swabs.

There are a few simple steps that can help to keep AC adapters from getting hot. First, be sure to use the adapter that was originally designed for the device. Also be sure to place the adapter on a hard surface away from any obstructions. If your adapter becomes excessively hot, check to be sure it is clean and free of damage.

While it’s important to use the correct voltage, using an adapter or charger with more amps typically will not burn the unit. Most devices will only draw the needed current, even if the adapter is a higher amperage.

Switching adapters are also referred to as switched-mode power supply. They are used to convert the voltage of an AC or DC input to a different voltage. Because they are generally smaller than other adapters, they can be helpful when being used in tight spaces. They also offer greater energy efficiency. However, they have been known to interfere with Wi-Fi reception because they generate high energy harmonics.

Let CDW help you choose the right AC adapter today.

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