AC Adapters
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An AC adapter or AC/DC adapter is a type of external
power supply A power supply is an electrical device that supplies electric power to an electrical load. The main purpose of a power supply is to convert electric current from a source to the correct voltage, current, and frequency to power the load. As a r ...
, often enclosed in a case similar to an
AC plug AC power plugs and sockets connect electric equipment to the alternating current (AC) mains electricity power supply in buildings and at other sites. Electrical plugs and sockets differ from one another in voltage and current rating, shape, si ...
. Other common names include wall wart, power brick, wall charger, and power adapter. Adapters for battery-powered equipment may be described as chargers or rechargers (see also battery charger). AC adapters are used with electrical devices that require
power Power most often refers to: * Power (physics), meaning "rate of doing work" ** Engine power, the power put out by an engine ** Electric power * Power (social and political), the ability to influence people or events ** Abusive power Power may a ...
but do not contain internal
component Circuit Component may refer to: •Are devices that perform functions when they are connected in a circuit.   In engineering, science, and technology Generic systems * System components, an entity with discrete structure, such as an assem ...
s to derive the required
voltage Voltage, also known as electric pressure, electric tension, or (electric) potential difference, is the difference in electric potential between two points. In a static electric field, it corresponds to the work needed per unit of charge to m ...
and power from
mains power Mains electricity or utility power, power grid, domestic power, and wall power, or in some parts of Canada as hydro, is a general-purpose alternating-current (AC) electric power supply. It is the form of electrical power that is delivered to ...
. The internal circuitry of an external power supply is very similar to the design that would be used for a built-in or internal supply. External power supplies are used both with equipment with no other source of power and with
battery Battery most often refers to: * Electric battery, a device that provides electrical power * Battery (crime), a crime involving unlawful physical contact Battery may also refer to: Energy source *Automotive battery, a device to provide power t ...
-powered equipment, where the supply, when plugged in, can sometimes charge the battery in addition to powering the equipment. Use of an external power supply allows portability of equipment powered either by mains or battery without the added bulk of internal power components, and makes it unnecessary to produce equipment for use only with a specified power source; the same device can be powered from 120 VAC or 230 VAC mains, vehicle or aircraft battery by using a different
adapter An adapter or adaptor is a device that converts attributes of one electrical device or system to those of an otherwise incompatible device or system. Some modify power or signal attributes, while others merely adapt the physical form of one c ...
. Another advantage of these designs can be increased safety; since the hazardous 120 or 240 volt mains power is transformed to a lower, safer voltage at the wall outlet and the appliance that is handled by the user is powered by this lower voltage.


Modes of operation

Originally, most AC/DC adapters were linear power supplies, containing a
transformer A transformer is a passive component that transfers electrical energy from one electrical circuit to another circuit, or multiple circuits. A varying current in any coil of the transformer produces a varying magnetic flux in the transformer' ...
to convert the
mains electricity Mains electricity or utility power, power grid, domestic power, and wall power, or in some parts of Canada as hydro, is a general-purpose alternating-current (AC) electric power supply. It is the form of electrical power that is delivered to h ...
voltage to a lower voltage, a
rectifier A rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which flows in only one direction. The reverse operation (converting DC to AC) is performed by an Power ...
to convert it to pulsating DC, and a filter to smooth the pulsating waveform to DC, with residual
ripple Ripple may refer to: Science and technology * Capillary wave, commonly known as ripple, a wave traveling along the phase boundary of a fluid ** Ripple, more generally a disturbance, for example of spacetime in gravitational waves * Ripple (electri ...
variations small enough to leave the powered device unaffected. Size and weight of the device was largely determined by the transformer, which in turn was determined by the power output and
mains frequency The utility frequency, (power) line frequency (American English) or mains frequency (British English) is the nominal frequency of the oscillations of alternating current (AC) in a wide area synchronous grid transmitted from a power station to th ...
. Ratings over a few watts made the devices too large and heavy to be physically supported by a wall outlet. The output voltage of these adapters varied with load; for equipment requiring a more stable voltage,
linear Linearity is the property of a mathematical relationship (''function'') that can be graphically represented as a straight line. Linearity is closely related to '' proportionality''. Examples in physics include rectilinear motion, the linear r ...
voltage regulator A voltage regulator is a system designed to automatically maintain a constant voltage. A voltage regulator may use a simple feed-forward design or may include negative feedback. It may use an electromechanical mechanism, or electronic components ...
circuitry was added. Losses in the transformer and the linear regulator were considerable; efficiency was relatively low, and significant power dissipated as heat even when not driving a load. Early in the twenty-first century,
switched-mode power supplies A switched-mode power supply (switching-mode power supply, switch-mode power supply, switched power supply, SMPS, or switcher) is an electronic power supply that incorporates a switching regulator to convert electrical power efficiently. Like ...
(SMPSs) became almost ubiquitous for this purpose due to their compact size and light weight relative to their power output ability. Mains voltage is rectified to a high direct voltage driving a switching circuit, which contains a transformer operating at a high frequency and outputs direct current at the desired voltage. The high-frequency ripple is more easily filtered out than mains-frequency. The high frequency allows the transformer to be small, which reduces its losses; and the switching regulator can be much more efficient than a linear regulator. The result is a much more efficient, smaller, and lighter device. Safety is ensured, as in the older linear circuit, because a transformer still provides
galvanic isolation Galvanic isolation is a principle of isolating functional sections of electrical systems to prevent current flow; no direct conduction path is permitted.John Huntington ''Show Networks and Control Systems: Formerly Control Systems for Live ...
. A linear circuit must be designed for a specific, narrow range of input voltages (e.g., 220–240 VAC) and must use a transformer appropriate for the frequency (usually 50 or 60 Hz), but a switched-mode supply can work efficiently over a very wide range of voltages and frequencies; a single 100–240 VAC unit will handle almost any mains supply in the world. However, unless very carefully designed and using suitable components, switching adapters are more likely to fail than the older type, due in part to complex circuitry and the use of semiconductors. Unless designed well, these adapters may be easily damaged by overloads, even transient ones, which can come from
lightning Lightning is a naturally occurring electrostatic discharge during which two electric charge, electrically charged regions, both in the atmosphere or with one on the land, ground, temporarily neutralize themselves, causing the instantaneous ...
, brief mains overvoltage (sometimes caused by an
incandescent light An incandescent light bulb, incandescent lamp or incandescent light globe is an electric light with a wire filament heated until it glows. The filament is enclosed in a glass bulb with a vacuum or inert gas to protect the filament from oxidat ...
on the same power circuit failing), component degradation, etc. A very common mode of failure is due to the use of
electrolytic capacitor An electrolytic capacitor is a polarized capacitor whose anode or positive plate is made of a metal that forms an insulating oxide layer through anodization. This oxide layer acts as the dielectric of the capacitor. A solid, liquid, or gel el ...
s whose
equivalent series resistance Practical capacitors and inductors as used in electric circuits are not ideal components with only capacitance or inductance. However, they can be treated, to a very good degree of approximation, as being ideal capacitors and inductors in series ...
(ESR) increases with age; switching regulators are very sensitive to high ESR (the older linear circuit also used electrolytic capacitors, but the effect of degradation is much less dramatic). Well-designed circuits pay attention to the ESR, ripple current rating, pulse operation, and temperature rating of capacitors. Many inexpensive switched-mode AC adapters do not implement adequate filtering and/or shielding for
electromagnetic interference Electromagnetic interference (EMI), also called radio-frequency interference (RFI) when in the radio frequency spectrum, is a disturbance generated by an external source that affects an electrical circuit by electromagnetic induction, electros ...
that they generate. The nature of these high speed, high-energy switching designs is such that when these preventative measures are not implemented, relatively high energy harmonics can be generated, and radiated, well into the radio portion of the spectrum. The amount of RF energy typically decreases with frequency; so, for instance, interference in the medium wave (US AM) broadcast band in the one megahertz region may be strong, while interference with the FM broadcast band around 100 megahertz may be considerably less. Distance is a factor; the closer the interference is to a radio receiver, the more intense it will be. Even WiFi reception in the gigahertz range can be degraded if the receiving antennae are very close to a radiating AC adapter. A determination of if interference is coming from a specific AC adaptor can be made simply by unplugging the suspect adapter while observing the amount of interference received in the problem radio band. In a modern household or business environment, there may be multiple AC adapters in use; in such a case, unplug them all, then plug them back in one by one until the culprit or culprits is found.


Advantages

External AC adapters are widely used to power small or portable electronic devices. The advantages include: * Safety – External power adapters can free product designers from worrying about some safety issues. Much of this style of equipment uses only voltages low enough not to be a
safety hazard A hazard is a potential source of harm. Substances, events, or circumstances can constitute hazards when their nature would allow them, even just theoretically, to cause damage to health, life, property, or any other interest of value. The probabi ...
internally, although the power supply must out of necessity use dangerous mains voltage. If an external power supply is used (usually via a power connector, often of coaxial type), the equipment need not be designed with concern for hazardous voltages inside the enclosure. This is particularly relevant for equipment with lightweight cases which may break and expose internal electrical parts. * Heat reduction – Heat reduces reliability and longevity of electronic components, and can cause sensitive circuits to become inaccurate or malfunction. A separate power supply removes a source of heat from the apparatus. * Electrical noise reduction – Because radiated electrical noise falls off with the square of the distance, it is to the manufacturer's advantage to convert potentially noisy AC line power or automotive power to "clean", filtered DC in an external adapter, at a safe distance from noise-sensitive circuitry. * Weight and size reduction – Removing power components and the mains connection plug from equipment powered by rechargeable batteries reduces the weight and size which must be carried. * Ease of replacement – Power supplies are more prone to failure than other circuitry due to their exposure to power spikes and their internal generation of
waste heat Waste heat is heat that is produced by a machine, or other process that uses energy, as a byproduct of doing work. All such processes give off some waste heat as a fundamental result of the laws of thermodynamics. Waste heat has lower utility ...
. External power supplies can be replaced quickly by a user without the need to have the powered device repaired. * Configuration versatility – Externally powered electronic products can be used with different power sources as needed (e.g. 120 VAC, 240 VAC, 12 VDC, or external battery pack), for convenient use in the field, or when traveling. * Simplified product inventory, distribution, and certification – An electronic product that is sold and used internationally must be powered from a wide range of power sources, and must meet product safety regulations in many jurisdictions, usually requiring expensive certification by national or regional safety agencies such as
Underwriters Laboratories The UL enterprise is a global safety science company headquartered in Northbrook, Illinois, composed of three organizations, UL Research Institutes, UL Standards & Engagement and UL Solutions. Established in 1894, the UL enterprise was founded a ...
or
Technischer Überwachungsverein TÜVs (; short for german: Technischer Überwachungsverein, en, Technical Inspection Association) are internationally active, independent service companies from Germany and Austria that test, inspect and certify technical systems, facilities an ...
. A single version of a device may be used in many markets, with the different power requirements met by different external power supplies, so that only one version of the device need be manufactured, stocked, and tested. If the design of the device is modified over time (a frequent occurrence), the power supply design itself need not be retested (and vice versa). *Constant voltage is produced by a specific type of adapter used for
computers A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations (computation) automatically. Modern digital electronic computers can perform generic sets of operations known as programs. These programs ...
and
laptops A laptop, laptop computer, or notebook computer is a small, portable personal computer (PC) with a screen and alphanumeric keyboard. Laptops typically have a clam shell form factor with the screen mounted on the inside of the upper li ...
. These types of adapters are commonly known as eliminators.


Problems

A survey of consumers showed widespread dissatisfaction with the cost, inconvenience, and wastefulness of the profusion of power adapters used by electronic devices.
Science fiction Science fiction (sometimes shortened to Sci-Fi or SF) is a genre of speculative fiction which typically deals with imaginative and futuristic concepts such as advanced science and technology, space exploration, time travel, parallel unive ...
author and
satirist This is an incomplete list of writers, cartoonists and others known for involvement in satire – humorous social criticism. They are grouped by era and listed by year of birth. Included is a list of modern satires. Under Contemporary, 1930-196 ...
Douglas Adams Douglas Noel Adams (11 March 1952 – 11 May 2001) was an English author and screenwriter, best known for ''The Hitchhiker's Guide to the Galaxy''. Originally a 1978 BBC radio comedy, ''The Hitchhiker's Guide to the Galaxy'' developed into a " ...
wrote an essay bemoaning the profusion and confusion of power adapters, and calling for more standardization.


Efficiency

The issue of inefficiency of some power supplies has become well known, with U.S. president
George W. Bush George Walker Bush (born July 6, 1946) is an American politician who served as the 43rd president of the United States from 2001 to 2009. A member of the Republican Party, Bush family, and son of the 41st president George H. W. Bush, he ...
referring in 2001 to such devices as "Energy Vampires". Legislation is being enacted in the EU and a number of U.S. states, to reduce the level of energy wasted by some of these devices. Such initiatives include
standby power Standby power, also called vampire power, vampire draw, phantom load, ghost load or leaking electricity ("phantom load" and " leaking electricity" are defined technical terms with other meanings, adopted for this different purpose), refers to ...
and the
One Watt Initiative The One Watt Initiative is an energy-saving initiative by the International Energy Agency (IEA) to reduce standby power-use by any appliance to no more than one watt in 2010, and 0.5 watts in 2013, which has given rise to regulations in many countr ...
. But others have argued that these inefficient devices are low-powered, e.g., devices that are used for small battery chargers, so even if they have a low efficiency, the amount of energy they waste is less than 1% of household consumption of electric energy. Considering the total efficiency of power supplies for small electronic equipment, the older mains-frequency linear transformer-based power supply was found in a 2002 report to have efficiencies from 20 to 75%, and have considerable energy loss even when powered up but not supplying power.
Switched-mode power supplies A switched-mode power supply (switching-mode power supply, switch-mode power supply, switched power supply, SMPS, or switcher) is an electronic power supply that incorporates a switching regulator to convert electrical power efficiently. Like ...
(SMPSs) are much more efficient; a good design can be 80–90% efficient, and is also much smaller and lighter. In 2002 most external plug-in "wall wart" power adapters commonly used for low-power
consumer electronics Consumer electronics or home electronics are electronic (analog or digital) equipment intended for everyday use, typically in private homes. Consumer electronics include devices used for entertainment, communications and recreation. Usually r ...
devices were of linear design, as well as supplies built into some equipment. External supplies are usually left plugged in even when not in use, and consume from a few watts to 35 watts of power in that state. The report concluded that about 32 billion
kilowatt-hours A kilowatt-hour (unit symbol: kW⋅h or kW h; commonly written as kWh) is a unit of energy: one kilowatt of power for one hour. In terms of SI derived units with special names, it equals 3.6 megajoules (MJ). Kilowatt-hours are a common bil ...
(kWh) per year, about 1% of total electrical energy consumption, could be saved in the United States by replacing all linear power supplies (average efficiency 40–50%) with advanced switching designs (efficiency 80–90%), by replacing older switching supplies (efficiencies of less than 70%) with advanced designs (efficiency of at least 80%), and by reducing standby consumption of supplies to not more than 1 watt. Since the report was published, SMPSs have indeed replaced linear supplies to a great extent, even in wall warts. The 2002 report estimated that 6% of electrical energy used in the U.S. "flows through" power supplies (not counting only the wall warts). The website where the report was published said in 2010 that despite the spread of SMPSs, "today's power supplies consume at least 2% of all U.S. electricity production. More efficient power supply designs could cut that usage in half". Since wasted electrical energy is released as
heat In thermodynamics, heat is defined as the form of energy crossing the boundary of a thermodynamic system by virtue of a temperature difference across the boundary. A thermodynamic system does not ''contain'' heat. Nevertheless, the term is al ...
, an inefficient power supply is hot to the touch, as is one that wastes power without an electrical load. This waste heat is itself a problem in warm weather, since it may require additional air conditioning to prevent overheating, and even to remove the unwanted heat from large supplies.


Universal power adapters

External power adapters can fail, and can become separated from the product they are intended to power. Consequently, there is a market for replacement adapters. The replacement must match input and output voltages, match or exceed current capability, and be fitted with a matching connector. Many electrical products are poorly labeled with information concerning the power supply they require, so it is prudent to record the specifications of the original power supply in advance, to ease replacement if the original is later lost. Careful labeling of power adapters can also reduce the likelihood of a mixup which could cause equipment damage. Some "universal" replacement power supplies allow output voltage and polarity to be switched to match a range of equipment. With the advent of switch-mode supplies, adapters which can work with any voltage from 110 VAC to 240 VAC became widely available; previously either 100–120 VAC or 200–240 VAC versions were used. Adapters which can also be used with motor vehicle and aircraft power ''(see
EmPower EmPower is a brand name that refers to three different power outlets available on commercial airlines: * 15-Volt, 75 Watt DC connector (now called EmPower Classic by the vendor) * 5-Volt, 10 Watt USB power-only jacks * 110-Volt, AC power jacks (some ...
)'' are available. Four-way X connectors or six-way star connectors, also known as spider connectors, with multiple plug sizes and types are common on generic power supplies. Other replacement power supplies have arrangements for changing the power connector, with four to nine different alternatives available when purchased in a set.
RadioShack RadioShack, formerly RadioShack Corporation, is an American retailer founded in 1921. At its peak in 1999, RadioShack operated over 8,000 worldwide stores named RadioShack or Tandy Electronics in the United States, Mexico, United Kingdom, Austra ...
sells universal AC adapters of various capacities, branded as "Enercell Adaptaplug", and fitted with two-pin female sockets compatible with their
Adaptaplug A coaxial power connector is an electrical power connector used for attaching extra-low voltage devices such as consumer electronics to external electricity. Also known as barrel connectors, concentric barrel connectors or tip connectors, these ...
connector lineup. This allows many different configurations of AC adapters to be put together, without requiring soldering. Philmore and other competing brands offer similar AC adapters with interchangeable connectors. The label on a power supply may not be a reliable guide to the actual voltage it supplies under varying conditions. Many low-cost power supplies are " unregulated", in that their voltage can change considerably with load. If they are lightly loaded, they may put out much more than the nominal "name plate" voltage, which could damage the load. If they are heavily loaded, the output voltage may droop appreciably, in some cases well below the nominal label voltage even within the nominal rated current, causing the equipment being supplied to malfunction or be damaged. Supplies with linear (as against switched) regulators are heavy, bulky, and expensive. Modern
switched-mode power supplies A switched-mode power supply (switching-mode power supply, switch-mode power supply, switched power supply, SMPS, or switcher) is an electronic power supply that incorporates a switching regulator to convert electrical power efficiently. Like ...
(SMPSs) are smaller, lighter, and more efficient. They put out a much more constant voltage than unregulated supplies as the input voltage and the load current vary. When introduced, their prices were high, but by the early 21st century the prices of switch-mode components had dropped to a degree which allowed even cheap supplies to use this technology, saving the cost of a larger and heavier mains-frequency transformer.


Auto-sensing adapters

Some universal adapters automatically set their output voltage and maximum current according to which of a range of interchangeable tips is fitted; tips are available to fit and supply appropriate power to many notebook computers and mobile devices. Different tips may use the same connector, but automatically supply different power; it is essential to use the right tip for the apparatus being powered, but no switch needs to be set correctly by the user. The advent of switch-mode power supplies has allowed adapters to work from any AC mains supply from 100 to 240 V with an appropriate plug; operation from standard 12 V DC vehicle and aircraft supplies can also be supported. With the appropriate adapter, accessories, and tips, a variety of equipment can be powered from almost any source of power. A "Green Plug" system has been proposed, based on
USB Universal Serial Bus (USB) is an industry standard that establishes specifications for cables, connectors and protocols for connection, communication and power supply (interfacing) between computers, peripherals and other computers. A broad ...
technology, by which the consuming device would tell the external power supply what kind of power is needed.


Laptop charger

In early laptop computers, the
power supply unit A power supply is an electrical device that supplies electric power to an electrical load. The main purpose of a power supply is to convert electric current from a source to the correct voltage, current, and frequency to power the load. As a res ...
s were internal like in
desktop computer A desktop computer (often abbreviated desktop) is a personal computer designed for regular use at a single location on or near a desk due to its size and power requirements. The most common configuration has a case that houses the power supply ...
s. To facilitate portability by sparing physical space and reducing the weight, power supply units were externalized. When a laptop computer is operated while recharging, the
integrated circuit An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuits on one small flat piece (or "chip") of semiconductor material, usually silicon. Large numbers of tiny ...
ry which controls the charging makes use of a power supply unit's remaining
electrical current Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by ...
capacity. This allows supplying the device's components with power during usage while maintaining an uncompromised constant charging speed.


Use of USB

The
USB Universal Serial Bus (USB) is an industry standard that establishes specifications for cables, connectors and protocols for connection, communication and power supply (interfacing) between computers, peripherals and other computers. A broad ...
connector (and voltage) has emerged as a de facto standard in low-power AC adapters for many portable devices. In addition to serial
digital data Digital data, in information theory and information systems, is information represented as a string of discrete symbols each of which can take on one of only a finite number of values from some alphabet, such as letters or digits. An example i ...
exchange, the USB standard also provides , up to ( over USB 3.0). Numerous accessory gadgets ("
USB decoration A USB decoration is a decorative device that uses the Universal Serial Bus (USB) connector for electrical power, and sometimes the protocol, on a computer or other host. In addition, some lightweight devices (e.g., a small lamp on a gooseneck sta ...
s") were designed to connect to USB only for DC power and not for data interchange. The
USB Implementers Forum The USB Implementers Forum (USB-IF) is a nonprofit organization created to promote and support USB (Universal Serial Bus). Its main activities are the promotion and marketing of USB, Wireless USB, USB On-The-Go, and the maintenance of the spe ...
in March, 2007 released the USB Battery Charging Specification which defines, "...limits as well as detection, control and reporting mechanisms to permit devices to draw current in excess of the USB 2.0 specification for charging ...". Electric fans, lamps, alarms, coffee warmers, battery chargers, and even toys have been designed to tap power from a USB connector. Plug-in adapters equipped with USB receptacles are widely available to convert or power or automotive power to USB power (see photo at right). The trend towards more-compact electronic devices has driven a shift towards the
micro-USB The initial versions of the USB standard specified connectors that were easy to use and that would have acceptable life spans; revisions of the standard added smaller connectors useful for compact portable devices. Higher-speed development of t ...
and
mini-USB The initial versions of the USB standard specified connectors that were easy to use and that would have acceptable life spans; revisions of the standard added smaller connectors useful for compact portable devices. Higher-speed development of ...
connectors, which are electrically compatible in function to the original USB connector but physically smaller. In 2012, a
USB Power Delivery Specification The initial versions of the USB standard specified connectors that were easy to use and that would have acceptable life spans; revisions of the standard added smaller connectors useful for compact portable devices. Higher-speed development of ...
was proposed to standardize delivery of up to 100 watts, suitable for devices such as
laptop computer A laptop, laptop computer, or notebook computer is a small, portable personal computer (PC) with a screen and alphanumeric keyboard. Laptops typically have a clam shell form factor with the screen mounted on the inside of the upper li ...
s that usually depend on proprietary adapters.


Standards

The ITU published Recommendation ITU-T L.1000, "Universal power adapter and charger solution for mobile terminals and other hand-held ICT devices", which specifies a charger similar in most respects to that of the GSMA/OMTP proposal and to the European Common external power supply. The ITU recommendation was expanded and updated in June, 2011. The hope is to markedly reduce the profusion of non-interchangeable power adapters. The
European Union The European Union (EU) is a supranational political and economic union of member states that are located primarily in Europe. The union has a total area of and an estimated total population of about 447million. The EU has often been des ...
defined a Common external power supply for "hand-held data-enabled mobile phones" (
smartphones A smartphone is a portable computer device that combines mobile telephone and computing functions into one unit. They are distinguished from feature phones by their stronger hardware capabilities and extensive mobile operating systems, which ...
) sold from 2010, intended to replace the many incompatible proprietary power supplies and eliminate waste by reducing the total number of supplies manufactured. Conformant supplies deliver 5 VDC via a micro-USB connector, with preferred input voltage handled ranging from 90 to 264 VAC. In 2006
Larry Page Lawrence Edward Page (born March 26, 1973) is an American business magnate, computer scientist and internet entrepreneur. He is best known for co-founding Google with Sergey Brin. Page was the chief executive officer of Google from 1997 unt ...
, a founder of
Google Google LLC () is an American multinational technology company focusing on search engine technology, online advertising, cloud computing, computer software, quantum computing, e-commerce, artificial intelligence, and consumer electronics. ...
, proposed a and up to standard for almost all equipment requiring an external converter, with new buildings fitted with wiring, making external AC-to-DC adapter circuitry unnecessary. IEC has created a standard for interchangeable laptop power supplies,
IEC 62700 IEC Technical Specification 62700: DC Power supply for notebook computer is an IEC specification of a common standard for external laptop computer AC adapters. Laptops and AC adapters following this standard will have interchangeable power supplies, ...
(full name "IEC Technical Specification 62700: DC Power supply for notebook computer"), which was published on February 6, 2014.


See also

*
AC power plugs and sockets AC power plugs and sockets connect electric equipment to the alternating current (AC) mains electricity power supply in buildings and at other sites. Electrical plugs and sockets differ from one another in voltage and current rating, shape, si ...
describes the usual sources of power for an AC adapter *
Adapter An adapter or adaptor is a device that converts attributes of one electrical device or system to those of an otherwise incompatible device or system. Some modify power or signal attributes, while others merely adapt the physical form of one c ...
*
Battery eliminator A battery eliminator is a device powered by an electrical source other than a battery, which then converts the source to a suitable DC voltage that may be used by a second device designed to be powered by batteries. A battery eliminator does awa ...
*
Coaxial power connector A coaxial power connector is an electrical power connector used for attaching extra-low voltage devices such as consumer electronics to external electricity. Also known as barrel connectors, concentric barrel connectors or tip connectors, these ...
has extensive coverage of the profusion of coaxial DC power connectors in use. * Common external power supply describes standards for mobile phone battery chargers. *
Ferrite bead A ferrite bead at the end of a Mini USB cable A ferrite bead (also known as a ferrite block, ferrite core, ferrite ring, EMI filter, or ferrite choke) is a type of choke that suppresses high-frequency electronic noise in electronic circuits. F ...
*
Power MOSFET A power MOSFET is a specific type of metal–oxide–semiconductor field-effect transistor (MOSFET) designed to handle significant power levels. Compared to the other power semiconductor devices, such as an insulated-gate bipolar transistor (IG ...
, widely used in most mobile device AC adapters. *
Power supply A power supply is an electrical device that supplies electric power to an electrical load. The main purpose of a power supply is to convert electric current from a source to the correct voltage, current, and frequency to power the load. As a r ...
describes other types of power supplies. *
Power supply unit (computer) A power supply unit (PSU) converts mains AC to low-voltage regulated DC power for the internal components of a computer. Modern personal computers universally use switched-mode power supplies. Some power supplies have a manual switch for select ...
*
Rectifier A rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which flows in only one direction. The reverse operation (converting DC to AC) is performed by an Power ...
, an electrical device that converts alternating current (AC) to direct current (DC) * Switched-mode power supply applications (SMPS) applications * USB Power describes the USB standards for DC power delivery to connected devices. *
Universal Power Adapter for Mobile Devices The Universal Power Adapter for Mobile Devices (UPAMD), codename IEEE 1823-2015 (before approval P1823), is an IEEE standard for power supply design intended to cater to the power range of (optionally for mobile devices like laptop computers. ...
*
Transformer A transformer is a passive component that transfers electrical energy from one electrical circuit to another circuit, or multiple circuits. A varying current in any coil of the transformer produces a varying magnetic flux in the transformer' ...
*
Electronic filter Electronic filters are a type of signal processing filter in the form of electrical circuits. This article covers those filters consisting of lumped electronic components, as opposed to distributed-element filters. That is, using components ...


References


External links


How to choose a wallwart for your small appliance, and how to get rid of them

External Power Supplies
Energy star information on external power supply specification and testing
TEST AC Power Adapters
By Jonathan Gordon, free iTunes eBook {{DEFAULTSORT:Ac Adapter Power supplies Repurposing ko:전원 공급 장치 ru:Блок питания