How to Choose Wall Mount Power Adapter?

Author: Cheryl

Apr. 28, 2025

How to Select the Right External Power Adapter - Astrodyne TDI

Whether you need an external power adapter for a new product or as a replacement for an existing product, finding the right one can be tricky. There are a few details that are important to consider when selecting an external power adapter, including its power and voltage specifications, which if selected appropriately will prevent certain issues that can lead to product failure.

How do you choose an external power adapter? This guide covers several parameters to consider when selecting the right external power adapter for your device or system.

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What Are External Power Adapters?

External power adapters are a type of power supply that plug into a wall outlet and convert alternating current (AC) to a direct current (DC) that powers certain electronic devices. They may also be called AC adapters, AC-DC adapters, AC-DC converters, DC power supplies, external adapter power supplies, or simply power adapters. 

External power adapters are used in a variety of applications, from sophisticated medical devices like circulatory pumps, ventilators, dialysis equipment, and telemedicine carts, to commercial or industrial manufacturing equipment like barcode scanners, weighing scales, and assembly line monitors, to consumer devices like laptop computers, computer monitors and printers. 

You can think of an external power adapter as a “black box,” with the AC input on one side and the DC output on the other side. It is typically offered in one of two styles, depending on the application requirements: wall mount or desktop. A desktop power adapter is designed to sit on the floor or a desktop and is typically shaped like a brick and has a power cord sticking out of one or opposite ends. A wall-mount power adapter has only an output cord at one end and includes power blades that protrude from the body of its case to plug directly into an AC wall socket.

A wall mount power adapter eliminates the need for an AC input cord but is limited to being used with the style of AC wall socket specific to a particular country unless it has an option for interchangeable AC plugs. A desktop adapter may include a captive AC cord and plug, which would have a similar limitation to a wall mount adapter, but most use a standard AC inlet that can accept different AC cords with plugs specific to whichever country in which they will be used. 

Most external power adapters available today – both wall-mount and desktop – can accept a “universal” AC input voltage of 90 to 264 volts AC (VAC). This voltage range will support the vast majority of countries, with the need to match only the AC input cord or wall plugs for a specific country; the power adapter itself can be used universally. This feature results in supply chain efficiency, and may even result in reduced product costs by leveraging volume manufacturing.

The main reasons for a product engineer to use an external power adapter over an internal (“embedded”) power supply in their system are size reduction and ease of replacement. By using an external adapter, the product itself can be made smaller (although the power adapter itself adds size back to the complete system – no free lunches!) And an external adapter can easily be replaced by a user, without the need for support from an experienced technician. The user simply needs to ensure that they have selected an adapter that will work with their product.

How Do I Know Which External Adapter to Use?

When choosing an external power adapter for any application, one must consider a few critical parameters to ensure that the adapter will perform effectively and safely:

AC Input Voltage

As previously mentioned, most external power adapters available today can accept a “universal” 90 to 264 VAC input voltage, which can support the vast majority of worldwide applications. In North America, domestic outlets supply 110-120 VAC. In Europe, they supply 220-240 VAC. Portable medical applications may require an AC input voltage as low as 85 VAC, and lighting applications often use a 277-205 VAC source. Note that some industrial and many infrastructure applications use a much higher AC voltage range, which would require different types of power converters.

DC Output Voltage

A product or device that is powered by an external power adapter requires a particular voltage, usually in a range from as low as 3.3 VDC to as high as 56 VDC, to operate correctly. An adapter must be selected with the appropriate matching DC output voltage, which will be marked on its label. Most adapters provide a single DC output, but some adapters provide two or three different output voltages (each with its power rating.) A selection of adapter models with standard output voltage increments are generally available, and custom models with non-standard output voltages can be provided from certain vendors, including Astrodyne TDI, as well.

Power Rating

One of the most important external power adapter specifications that is often overlooked is its output power rating. An adapter’s power rating is marked on its label, typically specified in Watts (W). This rating depicts the maximum power that can be reliably delivered from the adapter to the product being powered. The power rating of the adapter must always be equal to or greater than the power that will be consumed by the product being powered. Otherwise, undesirable results, such as reduced adapter lifetime, limited performance, or complete loss of functionality could occur.

It is important to note that an adapter's power rating is generally defined for use at room temperature. Operation at temperatures well above that - typically above 40-50 deg C (105 to 120 deg F) – may not support the full power rating. The datasheet for the adapter should include a power derate over-temperature graph, which details the maximum power that can be delivered at given operating temperatures.

Efficiency Rating

Recent commercial and industry regulations mandate minimum levels of power efficiency for external adapter power supplies. For example, in the United States, the Department of Energy instituted a requirement that beginning in , all external adapter power supplies introduced into the U.S. market (with a few exceptions, including adapters used to power FDA-approved medical devices) must meet Level VI efficiency requirements. Similar mandates exist in the European Union. 

Adapters that meet these U.S. requirements are usually marked with the roman numeral VI enclosed in a circle. Older designs marked with roman numerals IV or V are no longer approved for U.S. market introduction. Many external power adapter manufacturers still provide solutions that do not meet the new requirements, so it is important to confirm what is needed for a particular application and whether the power supply being considered conforms to the applicable mandates.

Connectors

Connectors that are appropriate for each application will need to be selected for both the AC input and the DC output of the external adapter power supply. For the AC input, a common practice for desktop adapters is to use an IEC320-C14 or -C8 inlet, to which standard power cords with wall socket plug ends suitable for use in specific countries can be separately attached. Alternately, a captive AC input cord may be used, with a wall socket plug specific to a particular country or country. Wall mount adapters will require fixed blades specific to the country of use, or a selection of interchangeable blades that can support a variety of countries.

A great diversity of DC power connectors are required by the innumerable applications that can use external power adapters. System designers tend to make their own decisions on what connector they prefer, and it is usually straightforward to accommodate almost most requests. The most common standard DC connectors are female barrel plugs, which are two-conductor (output voltage and return) solutions that are also available in a variety of sizes.

The four main parameters that need to be specified for a barrel plug are inner diameter, outer diameter, barrel length, and polarity - whether the center contact is the output voltage (standard configuration) or the return. Other barrel plug features include whether there is a “locking” mechanism, such as a screw-on collet, to secure the plug to the jack on the device being powered. Other types of common connectors include multi-pin DINs and “Molex” style pin/socket receptacles.

Safety Certifications

Finally, external power adapters will require safety certifications specific to the applications and countries in which they will be used. There are different certification standards for medical applications than there are for commercial/industrial applications, and each country or region requires its certifications as well. Astrodyne TDI offers adapters with either medical or safety certifications (and sometimes both), for standard use in the U.S., Canada, and the European Union. Additional country safety certifications, and certification to other standards, can be obtained upon request.

Contact Us With Any Questions

How to Choose Power Adapters to Safeguard Electronic Devices?

How to Choose Power Adapters to Safeguard Electronic Devices?

Overviews

  • What is a Power Adapter? What are the Applications?
  • How do Power Adaptors Work? How to Ensure the Safe Use of Electronic devices?
  • How to pick a Power Adapter? FSP's Power Adapter purchase recommendations

Power Adapters are ever-present in our everyday life. Many people use power supplies every day, but do not necessarily understand them. Some people call a Power Adapter in Chinese an a/c adaptor, while some brands call them adapter to better sell. However, “external power supply” is the correct name.

A Power Adapter is a power supply device that helps input current and conversion into power supply for electronic devices and electrical appliances. Therefore, if the right product fails to be picked, or if a product with poor quality and error is chosen, it will damage electronic devices and electrical appliances, but it can also cause injuries to users.

Related links:
Is a 90W Desktop Power Adapter Worth It?

You will get efficient and thoughtful service from Teng Da Xing.

Just how should a Power Adapter be selected correctly? Let professional manufacturers FSP Group who have cultivated the power supply market for nearly 30 years, give you an insight into Power Adapters and how to go about choosing them.

What is a Power Adapter? What are the Applications?

Various products we use in everyday life, such as computers, come with an internal power supply device. However, such products as thermal printers, small ATM machines, credit card machines, or handheld POS machines sometimes cannot accommodate power supply devices due to their mini sizes. External power supplies may be used if other product structure design considerations exist.

Let us not underestimate power adaptors that are small and carried around in a bag. They are the heart of electronic devices and appliances. A bad choice may deprive us of the chance to use these products properly, leading to a shorter product life.

How do Power Adaptors Work? How to Ensure the Safe Use of Electronic devices?

The basic operational principle of Power Adapters focuses on power generated depending on different countries’ use of electricity at different voltages, as well as conversion to “suit” product use. Basically, through modern electronic technology, the power supplies and management devices maintain the stability of output voltages. 

Conversion efficiency is an existential issue when a Power Adapter is at work. When the input power is 100W, the conversion output is lower than 100W. The redundant power will generate and dissipate heat. Therefore, the key technology in the Power Adapter design is heat dissipation from the outer casing. A poor design may result in a low temperature burn during the use.

As an external power supply device, a power adapter may be small in size, but it actually has a considerable technical threshold. Each electrical appliance with a built-in motor must import a voltage start motor with higher power when turning on. How to achieve high output within a short period of time and power stability for a long time, small volume, high heat dissipation, and safety, taking into account the Power Adapter's long service life and all-rounded aspects, the manufacturer's technology is put to the test.

After learning about how a Power Adapter works and why it is needed, it is more important to recognize how to pick a good Power Adapter. In particular, if you often go on business trips in different parts of the world and an external power supply is needed at all times, things may go wrong when there is an emergency if you choose the wrong product.

Is a Power Adapter suitable? First, usage situations are taken into account. A Power Adapter can be divided into two types: desktop and wall mount. Wall-mount power supplies have been designed with a plug directly plugged into a socket on the wall, while both sides of the desktop have power lines for more flexible use, which can be purchased based on actual user needs.

Regardless of the type of Power Adapter, whether the input plug specifications are in line with the local socket in a country is the most important. If the specifications are non-conforming, a universal adapter will need to be purchased. Additionally, when it comes to the specifications of tip heads used to connect electrical appliances, the tip head type should be noted if a power supply needs to be separately purchased, to prevent not being able to use it after it is purchased.

There will be socket specification differences at the connecting power line if it is a desktop external power supply. Currently, the standard specifications include: C14 (vertical, three-hole), C8 (round, figure-8 2-hole), and C6 (Mickey Mouse-shaped hole). This is the focus to be considered during AC power Cord selection.

Of course, as a power supply, “electricity” is the key. Read information on the product or package label in order to understand if a power adaptor is suitable. An assessment covers three basic aspects.

  1. Safety Standard Approval;
  2. Energy Efficiency level;
  3. Input and output power labeling

The most basic requirement for a certified power adaptor is to obtain safety certifications from different countries. Manufacturers usually include these certifications on the label. Each country has its own set of safety specifications, and the most universally used is of course the U.S. (UL/cUL) certification. The EU CE-Marking Low Voltage Directive (LVD) is in line with the declaration and China’s CCC certification.

Every country varies in the safety certification requirement focus. Take the EU CE-Marking Low Voltage Directive (LVD), for instance. It has stricter environmental protection specifications compared to other countries. The higher the number of safety certifications obtained, the more easily it is to sell a Power Adapter across the world, with higher applicability.

The acquisition of safety certifications is only but a basic requirement for external power supplies. Whether the DoE efficiency level label is on the label needs to be further examined. In order to sell products in the U.S. market, the DOE’s mandatory specification for efficiency level is Level VI.

Worth noting is that a mandatory requirement of DoE is that the efficiency level of imported products must be labeled. On the other hand, although the European Union also has regulations that products must meet CoC efficiency standards, DOE’s specifications may also serve as the standard. Therefore, clearly listing the efficiency level on the label is the basic criterion for Power Adapter selection.

More importantly, whether a Power Adapter meets one’s own needs can be verified through AC INPUT and DC OUTPUT labels.

The AC volts (V) input represents the countries intended. The country with the lowest AC voltage is Japan (100V), while Europe, the United Kingdom, and China have the highest voltage of 240V. If a Power Adapter’s AC input is labeled 100-240V, it means it can be used in all the countries around the world.

For Power Adapters to be used in different countries, they must supply adequate power to be used. For this part, the volts (V) and amperage (A) displayed in the DC output are multiplied to derive the power supply wattage. This is then compared to the product ready to be used to determine if the power supply requirements are met.

How to pick a Power Adapter? FSP's Power Adapter purchase recommendations

Before selecting a power supply, we must first confirm the best performance of the device in order to select a complementary power supply. FSP provides the universal form of Power Adapters below as a reference for everyone during selection.

As small as a power adopter is, great wisdom is involved. In addition to putting the manufacturer’s technology to the test, many consumers do not have a clue when choosing one to buy. By now, hopefully, everyone already knows how to pick an external power supply. A good Power Adapter has a long service life, and it can ensure the lifespan and safety of electronic devices, and electrical supplies. Caution must be taken!

Contact us to discuss your requirements of Wall Mount Power Adapter. Our experienced sales team can help you identify the options that best suit your needs.

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