What is AC/DC Power Adapter?

This page explains the theme of what an AC/DC Power Adapter is, providing easy-to-understand basic knowledge such as pin types and shapes, enclosure differences, and the history and features of AC/DC Power Adapter, from the perspective of a power supply manufacturer specializing in AC/DC Power Adapter.

More specifically, an AC/DC Power Adapter is an electronic device used for electrical Products (devices) that require power. Rather than drawing the required power directly from the main power source, it converts the commercial power supply provided by power plants and other sources from AC to DC, or transforms the voltage. In Japan, the voltage of the commercial power supply is 100V, and the frequency ranges from 50Hz to 60Hz.

The internal circuit design of an AC/DC Power Adapter is very similar to that of a built-in or internal power supply.

• 《For an explanation of AC/DC Power Adapter circuits, please see What is the mechanism of an AC/DC Power Adapter?》
• 《For an explanation of the role of an AC/DC Power Adapter, please see What is the role of an AC/DC Power Adapter?》
• 《To learn how to use and maintain an AC/DC Power Adapter for as long as possible, please see How to Use and Maintain an AC/DC Power Adapter》

AC/DC Power AdapterRequired Electrical Products (Devices)?

Devices that require an AC/DC Power Adapter can be broadly divided into the following:

• Electrical Products (devices) without a built-in power source
• Battery-powered electrical Products (devices)

By plugging the AC/DC Power Adapter into an AC outlet and connecting the power supply, it becomes possible to supply power to the electrical Products (devices) or charge their batteries.

As described later in the [Summary of Advantages When Using an AC/DC Power Adapter], using an AC/DC Power Adapter eliminates the need to install an internal power supply in the main unit of the electrical Products, making it possible to carry devices powered either by a main power source or a battery.

In addition, if you want to supply power to the same electrical Products (device) from a 100VAC or 240VAC main power source, or from a vehicle or aircraft power source, you can enable a wide range of uses simply by preparing a compatible AC/DC Power Adapter. This eliminates the need to manufacture electrical Products that can only be used with a specific power source.

Furthermore, using an AC/DC Power Adapter can enhance safety. Commercial power supplies of 100V/240V (100V in Japan), which can be fatal in the event of electric shock, are converted into a safe low voltage, allowing power to be supplied to user-operated devices at a lower voltage.

Types and Shapes of AC Pins

AC pins include foldable types and interchangeable types compatible with standards in various countries. Our company has a proven track record of supplying AC/DC Power Adapter worldwide and can provide AC pins בהתאם to the destination country.

The table below introduces the main types and shapes of AC pins.

Type A

Japan, United States, Canada, Mexico, parts of South America including Brazil, Taiwan, China (Central and Northern regions), and parts of Thailand

Type A (No pin hole required, China certified type)

Round 2-Pin

European countries and former European territories, South Korea, Vietnam, Cambodia, Indonesia, India, Egypt

Type O

Oceania regions such as Australia and New Zealand, Central and Northern China, Argentina, Philippines

Type BF

United Kingdom, Hong Kong, Singapore, China, Malaysia

AC/DC Power Adapter Features?

Adapter shapes include L-shaped, straight type, and inlet type, and in recent years various shapes of AC/DC Power Adapter have been introduced to match the design of the main device.

In addition to the above shapes of AC/DC Power Adapter, we also offer round housing AC/DC Power Adapter.

The AC input inlet of inlet type AC/DC Power Adapter is broadly classified into three types: IEC60320-C1, commonly known as the "pig nose" type; IEC60320-C7, commonly known as the "figure-8" type; and the 3-pole IEC60325-C5 and IEC60320-C14.

AC/DC Power Adapter Selection Tips

How to Choose a AC/DC Power Adapter for Longer Use

It is generally said that selecting a model with a rated output 30% higher than required allows the AC/DC Power Adapter to be used for a longer time.

For example, if a device that uses an AC/DC Power Adapter requires 60W of power, it is recommended to select a model with a rated output of 75W or higher. Long-term use at the absolute limit of the rated capacity may prevent the lifespan from being effectively extended.

Pay Attention to the Operating Environment

When selecting a model, it is necessary to consider the operating temperature of the AC/DC Power Adapter and whether there is external heat dissipation equipment. If the adapter will be used in a high ambient temperature or under other specific conditions, please contact our sales department.

Select the Correct DC Plug

If the correct DC plug is not selected, the device may not operate or could result in an unexpected accident. It is necessary to properly check the DC plug polarity, such as center positive or center negative, as well as the EIAJ voltage classification. DC cable lengths also vary.

Consider the Peak Current of the Device

For devices that use motor drive systems, such as dental equipment, printers, sewing machines, electric shavers, and massage devices, it is necessary to select an adapter that takes peak current into consideration. UNIFIVE offers a lineup of AC/DC Power Adapter that support peak currents of up to twice the rated current for durations from 1 to 10 seconds.

Check the Safety Standards of the Products

Depending on the type of device using the AC/DC Power Adapter, the required safety standards and technical requirements will vary. For example, medical standards apply when used for medical equipment, and harmonic current standards apply when used for LED devices. In addition, the adapter must comply with the safety standards and technical regulations of the destination country. Attention must also be paid to efficiency standards such as DoE, ErP, and FCC.

AC/DC Power Adapter History

Part 1: The Emergence and Disadvantages of Linear Power Supplies

Originally, an AC/DC Power Adapter referred to a linear power supply (dropper) consisting of a transformer to convert commercial power to a lower voltage, a rectifier to convert it to DC, and a filter to smooth the pulsating waveform, which had a significant ripple effect on the connected device. However, for ratings above 10W, this "linear power supply" used a large transformer, resulting in a larger adapter size and heavier weight, making it physically difficult to support on a wall outlet.

The output voltage of a linear power supply AC/DC Power Adapter generally varies depending on the load. For devices requiring a stable voltage, a linear voltage regulator was added to the circuit, but the efficiency was not high and losses were significant. Therefore, power was consumed even under no-load conditions, and the loss was dissipated as heat.

Part 2: The Emergence of Switching Power Supplies

At the beginning of the 21st century, in order to overcome the disadvantages of the linear power supplies mentioned above, switching DC regulated power supplies called SMPS (Switch Mode Power Supply) became mainstream.

In a switching power supply, the input AC voltage is directly rectified by a diode bridge rectifier, smoothed by an aluminum electrolytic capacitor, and then transmitted to the secondary side through rapid on/off switching of switching elements. This high-frequency switching enables the use of a smaller transformer and reduces losses compared to linear systems. In addition, high-frequency ripple can be easily removed. Therefore, switching regulators are far more efficient than linear regulators, enabling lightweight and compact designs.

Some may wonder whether a small transformer is sufficient, but SMPS transformers use galvanic isolation to ensure safety.

Linear power supply circuits are designed with a narrow range of input voltage (e.g., AC95V~105V) and typically use transformers suitable for frequencies of about 50 or 60Hz. In contrast, switching power supplies operate efficiently over a very wide range of input voltage and frequency. They cover 100VAC to 240VAC and support nearly all global commercial power sources. This is the so-called universal type.

However, these switching DC regulated power supplies are also vulnerable to overload caused by lightning and ESR-related issues. Customers concerned about lightning strikes or who require operation over a wide temperature range are advised to select our models designed with thorough measures against ESR and ripple noise, lightning surge protection, and temperature range countermeasures.

Part 3: The Spread of USB AC/DC Power Adapter

In recent years, USB connectors have been adopted for many portable devices. In addition to data transmission, they can supply output DC5V at up to 500mA (up to 900mA with USB3.0) to devices. A wide variety of equipment, from portable batteries and coffee makers to small lamps and alarm clocks, is now designed to receive power from USB connectors. In 2012, USB Power Delivery, which standardizes power supply up to 100W, was proposed and has gradually become widespread.

Recently, AC/DC Power Adapter miniaturized using GaN devices have appeared, offering more portable Products.

AC/DC Power Adapter Summary of Advantages of Using

On the page Advantages and disadvantages of using an AC/DC Power Adapter versus directly using AC power on our website, we briefly introduce the advantages and disadvantages of using an AC/DC Power Adapter. Here, we will provide a more detailed summary.

No.1: Safety

By adopting an AC/DC Power Adapter, designers of electrical Products can design the main device without being subject to safety regulations mandated by the destination country.

No.2: Reduced heat from the main device power supply

For electrical Products, heat is a major enemy. As temperature rises, it affects the lifespan and reliability of electronic components and may cause delicate circuits to malfunction. By using an external power supply, it is possible to eliminate heat generated by the internal power supply of the Products itself.

No.3: Reduced noise impact on the main device

It is possible to reduce electrical noise that can negatively affect noise-sensitive circuits in the main device. Since electrical noise decreases in proportion to the square of the distance, increasing the distance by using an AC/DC Power Adapter helps reduce its impact.

No.4: Lighter weight and smaller size of the main device

By using an external power supply, the main device itself can be made smaller accordingly.

No.5: Easier maintenance of the main device

Compared to other circuits, power supplies are more vulnerable to output spikes and heat generated by the main device, making them more prone to failure. By using an external power supply, even if a failure occurs, users can easily replace it themselves, eliminating the need to repair the entire main device.

No.6: Improved convenience

Main devices that adopt an AC/DC Power Adapter can support various voltages as needed.

(For example, by adopting a universal-type AC/DC Power Adapter, power can be obtained from outlets around the world without any problems.)

This article is partially related to information we provided when our company cooperated in the production of NHK "Chico-chan ni Shikarareru!" as content related to the mechanism of AC/DC Power Adapter.

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