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📢 | Can be used for teleworking! Portable and compact LED light that can be attached with a magnet is now on sale.


Can be used for teleworking! Portable and compact LED light that can be attached with a magnet is now on sale.

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The power supply can be used by connecting it to the USB port or by connecting it to the included AC adapter.

From the lighting brand <MotoM>, which is easy to use and has a stylish feel, January 2021, 1 (... → Continue reading

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AC adapter

AC adapterWhat is (AC Adapter)?

  1. Commercial power supplyThanAlternating currentA device that inputs and outputs the desired power.Details are given in this section.
  2. A common name for an AC-DC adapter (a device that extracts the desired DC power from a commercial power source). Both AC adapter and DC adapter.

AC adapter(AC adapter) is smallHome appliancesUsed in, etc.Power supply.


Power companySupplied fromCommercial power supplyIs generally over 100VAlternating currentIs.On the other hand, many electric appliances that consume electric power use direct current of around 3 to 12V.Transformer,rectifierWith a power supply device consisting of a stabilizing circuit, etc.DCWill need to be converted to.The AC adapter is a physically separated and independent power supply device.

Normal,ElectronicsMostly used in a class of electrical appliances called, such as lighting equipment and washing machines fixed to buildings.Electrical appliancesIt is rarely used in large electric appliances in the category called. The AC adapter was originallyTrannyIt was often used in battery-powered portable electronic devices such as the above, but today it is also used in non-battery-powered electronic devices and small electric appliances due to reasons such as separation of heat sources and ease of design. Opportunities for AC adapters to be used are increasing.Most AC adapters convert AC power to DC power.AC-DC adapterHowever, the AC output for the purpose of transformer onlyAC-AC adapterIs also called an AC adapter.

As a typical example of using an AC adapterMobile phone,Portable music player,Portable game console,laptopThere are devices that are supposed to be carried around and used.In the following cases, even if the device is large enough to have a built-in power supply, it may not have a built-in power supply and may be separated from the main unit as an AC adapter.

  • The main body emits powerheat,noiseTo make it less susceptible to
  • To improve the design and miniaturization of the main body
  • To improve overall maintainability
  • To respond to plug shapes, voltages, and voltage fluctuations that differ depending on the country / region
  • Because the main body can be designed without being regulated by the laws of each country (Japanese Electrical Appliance and Material Safety Law)
  • To reduce the cost of the main unit

Built-in rechargeablePower Input(Secondary battery), The main purpose of the AC adapter is to supply the current to charge the battery.AC adapters for these devices, such as mobile phonesChargerSometimes called (charger, judenki).Mobile phones and game consoles are equipped with a charge control circuit on the main unit side, and the AC adapter operates as a general power source.Radio-controlled cars, etc. have a charge control circuit inside the AC adapter.

electric circuit

The AC adapter (AC-DC adapter) isOutletThe AC power obtained from the insideTransformerAfter lowering (stepping down) the voltage with (transformer)rectifier(diode) BySeries regulatororSwitching regulatorIt outputs stabilized DC power via a stabilizing circuit such as.Small capacity ones do not have a stabilizing circuit, transformers and rectifiers, simple smoothing circuits (large capacity)CapacitorThere is also an unstabilized AC adapter that consists only of).In addition, some switching AC adapters are transformerless without using a transformer.

In addition, since the 1990s, a switching method that directly rectifies AC power obtained from an outlet, converts it to high-frequency AC, then steps down with a small transformer to rectify and smooth it.Switching power supplyHas become mainstream.Compared to conventional AC adapters, the number of parts is larger and the cost is higher, but since it is possible to use a small transformer or eliminate the need to use a transformer, it leads to smaller and lighter equipment, and power conversion efficiency is also improved. It is characterized by being expensive.However

The power loss that occurs when converting from AC to DCheatThe AC adapter in use often has heat because it is released in the form of energy. Series regulatorIf a regulated power supply circuit using is installed, the heat loss in this part is very large.Switching regulators also generate heat, but tend to be less than series regulators.In a similar circuit configuration, the larger the capacitance, the more heat tends to be generated.For large AC adapters, for coolingフ ァ ンEquipped withForced air coolingSome say that.

Even when not in use, the AC adapter is weak due to the internal circuit configuration.電流Is flowing. Standby powerIt is desirable to disconnect the AC adapter of unused equipment from the outlet in order to reduce the number of problems.The AC adapter is a device intended for conversion from AC to DC (forward conversion), and conversion from DC to AC (forward conversion).Inverse conversion) Is impossible.

Appearance / shape

If you extract the characteristic parts from the appearance of a general AC adapter, you can see that it is roughly divided into three parts.That is, plug it into an outletPlug part, Transformer circuit, rectifier circuit, stabilized power supply circuit, etc.Body part, And supply DC power to electrical equipmentOutput partIs.Of these, regarding the plug part that plugs into the outlet, there are those that are directly attached to the main body and those that have a cable extending from the main body, and the latter has a cable that is further fixed and a detachable power cord shape. It is divided into what to take.The output part often consists of a cable fixed directly from the main body and a DC plug attached to the tip of the cable.

Body part

The shape of the housing of the AC adapter is generally box-shaped. blackColor or dark grayPlasticAnd the rating and safety standards are shown on the surfacePSEMark andULmark,GSmark,,,,,,CCC,CSA,VDE,GOST R, And, etc. are described, and multiple marks are described for those with specifications common to each country. A common certificate mark for EMI / RFI isCE markWhen,FCCWhen,.These marks are indispensable for power supply equipment connected to commercial power supplies in each country, and the mark display is written on those certified as proof of having undergone quality inspection.In recent years, many have emphasized design, using bright colors and having an appearance that is far from a rectangular parallelepiped.For exampleア ッ プ ルEtc. are developing an AC adapter with a design that is consistent with the main unit.In general, there is a tendency for designs that take portability and storability into consideration for items that are often carried around, such as for laptop computers.

The size of the main body is determined by the circuit configuration of the AC adapter and the size of the output power.Generally, if you use a series regulator,TransformerMeasures to release heat from the (transformer) and regulator (heatsinkEspecially for high outputフ ァ ンEtc.), which makes it heavy and bulky.On the other hand, the one using a switching regulator is compact because the circuit itself is small and generates less heat.Further, depending on the equipment to be combined, the stabilization circuit may be simplified or omitted, and in that case, further miniaturization may be possible.Further, even if the circuit configuration is the same, the larger the output power, the larger the size of the component and the larger the heat generation, and as a result, the overall size increases.

For devices that require portability (mobility), it is preferable that the AC adapter is also compact.A large AC adapter may be required for the main body of a notebook computer with high power consumption, but recently, the AC adapter is becoming smaller due to a small and high-performance switching regulator.

Portable music playerIn audio equipment such as, in consideration of the adverse effect of noise generated by the switching regulator, there are many cases where an AC adapter using a series regulator is combined, and the AC adapter may be one size larger than the main body of the equipment.

Input part

AC power is usually supplied to the AC adapter from a household commercial power outlet.Some outlet plugs are directly attached to the AC adapter body, while others have a cable extending from the body and attached to the tip.In the latter case, many cables can be attached and detached.

Most of the AC adapters have a connector directly attached to the main body of the AC adapter, but there is a problem that it often blocks the hole of the adjacent outlet, and improvement is desired.This can be solved by using extension cords, and very short extension cords are also available on the market.Some of them can be stored compactly by folding the plug part, which can be said to be an excellent improvement from the viewpoint of portability, storability, and safety.If you accidentally step on the AC adapter placed on the floor with the plug facing up, the plug part may bend and become unusable, and there is a risk of damaging the soles of your feet.

In that respect, the one with the connector attached to the end of the cable is much easier to handle.In the case of a relatively large and heavy AC adapter, even if the outlet plug is attached directly to the main body, it is not possible to support its own weight with the outlet plug alone, so this form is inevitably taken.

If the power cable can be attached and detached, it can be used in foreign countries with different plug shapes by replacing it.In Japan, the connection between the power cable and the AC adapter body has a cross section in the shape of the number "8".Glasses codeBipolar connector commonly known as (IEC 60320/ J60320 C7) is often used, and tripolar cables (commonly known as 2P-3P AC cords), which are often found in PC power cables such as products made by overseas manufacturers.ミ ッ キ ーcable IEC 60320/ J60320 C5) is often used.

Some AC adapters are said to be compatible worldwide and support input voltages in the range of 100 volts AC to 240 volts AC.Detachable AC side cables for such products sold in Japan may have a label such as "7A 125V".

Output part

It is converted to direct current, and in many cases the output power is transmitted by a thin, supple, stranded cable and connected to the device by a connector.The size, shape, and number of terminals of the connector vary depending on the voltage and capacity.

The shape of the connector, pin layout, and voltage range are unified.EIAJ Polarity unified plug(EIAJ RC-5320A) also exists, but it is a later standard[1]Therefore, a connector conforming to the abolished old standard EIAJ RC-6705 (outer diameter 5.5 mm, inner diameter 4.0 mm, length 9.5 mm)[2]Is more widely used.AlsoIEC 60130-10 andDIN Various connectors specified in 45323, EIAJ RC-5322 connectors for in-vehicle devices (outer diameter 6.5 mm, inner diameter 3.1 mm, pin diameter 1.0 mm, length 9.5 mm)[3]In some cases, the manufacturer's original connector is used.

Regarding the polarity, the equipment that uses the EIAJ polarity unified plug is unified to Center Plus.Most of the devices that use plugs of other standards use Center Plus for devices after the mid-1990s, but Center Minus is the mainstream for audio equipment, musical instruments, and effectors.

Japanese old mobile phone (feature phone) AC adapter, external connection terminal (EIAJ RC-5238 "IMT-2000 mobile phone connector A", CDMA Type Cellular Phones NC-R 1-18 "CDMA mobile phone terminal" unified for each mobile phone standard Some use the "interface connector").However, even if the terminals are unified, the voltage and current may not be unified (PDC,CDMA 1X In that case, a protrusion called a key is provided on the terminal so that it can only be connected by the same manufacturer.

またUSBThere is also a general-purpose AC adapter that has the same mechanical USB terminal and has the function of supplying power to the power supply terminal for use in devices that operate and charge with the bus power of.However, according to the USB standard, negotiation by data communication is required to output a current of 500mA or more, but there is also a standard violation product that can output up to about 1A without negotiation, which is called charging only.

Main plug standards (length 9.5 mm, current maximum 2 A)
Standard numberOuter diameter (mm)Inner diameter (mm)Pin diameter (mm)Corresponding voltage (V)
EIAJ RC-6705
EIAJ RC-53226.53.11.0-
#24.01.7-3.15 ~ 6.3
#34.751.7-6.3 ~ 10.5
# ~ 13.5
# ~ 18

Use of compatible products

When using the AC adapter, it is desirable to use the accessories of the device or the products specified by the manufacturer.[4]..However, output voltage / current[5]-If the shape of the connector and the polarity of the connector are the same and the transformation method (transformer method / switching method) is the same, there is no problem in practical use even with compatible products.However, measuring equipment and audio equipment (electronic musical instruments,effector・ For musical instrumentsAmplifier-Luxury audioEtc.), etc. for design reasonsHum noiseWhen using it in precision equipment that is sensitive to the noise, it is necessary to consider the amount of ripple noise and spike noise.You can also connect equipment without a regulated circuit to equipment designed for a regulated power supply.Series regulatorInstead ofSwitching regulatorIf you connect something, it may cause malfunction or failure.In particular, a transformer-type AC adapter that does not have a stabilizing circuit outputs a higher voltage than indicated when there is no load, so there is a risk of damaging the circuit if it is connected to other equipment unnecessarily.There is also a highly versatile AC adapter with a variable output voltage so that it can be used in common with various devices.In such products, it is generally possible to replace the tip of the plug with the connector of the device to be used.

Related standards


An example of an AC adapter


[How to use footnotes]
  1. ^ Established in September 1989
  2. ^ The same is specified in IEC 60130-10 "Connectors for frequencies below 3 MHz. Part 10: Connectors for coupling an external low-voltage power supply to portable entertainment equipment".
  3. ^ The voltage is 12V or 24V, and the maximum current is 2A.
  4. ^ In JEITA ET-2502A "Display items and display methods for devices that use DC plugs and jacks," the notation example used to call attention is "If you use an AC adapter other than the one provided, it may cause a malfunction." " Please use only the designated device. Never connect to other devices. "
  5. ^ Since this is the upper limit of the supply current, it may be slightly larger.

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