Coaxial power connector

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Most common coaxial power connector, male and female, 5.5 x 2.5 mm
Common DC power connectors

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 small cylindrical connectors come in an enormous variety of sizes.

Barrel plug connectors are commonly used to interface the secondary side of a power supply with the device. Some of these jacks contain a normally closed switch; the switch can disconnect internal batteries whenever the external power supply is connected.

Connector construction and terminology[edit]

Female (plug)[edit]

On the female plug, the outer body is metallic and cylindrical in shape, and comprises one of the two contacts. The second, inside contact is a hollow metallic cylinder constructed to accept insertion of the pin in the corresponding male connector. The inner and outer barrels are separated by an insulating layer. The outer contact is generally called barrel or sleeve, and the inner contact is called the tip.

Male (receptacle)[edit]

There is typically a single spring-loaded contact at the side of the male connector and a pin in the center corresponding to the intended female plug.

Connector sizes[edit]

There are many different sizes of coaxial power connectors (see table at end of this article).

Contact ratings commonly vary from unspecified up to 5 amperes (11 amperes for special high-power versions). Voltage is often unspecified, but may be up to 48V with 12V typical. The smaller types usually have lower current and voltage ratings.

It is quite possible that new sizes will continue to appear and disappear. One possible reason that a particular manufacturer may use a new size is to discourage use of third-party power supplies, either for technical reasons or to promote use of their own products, or both.

The sizes and shapes of connectors do not consistently correspond to the same power specifications across manufacturers and models. Two connectors from different manufacturers with different sizes could potentially be attached to power supplies with the same voltage and current. Alternatively, connectors of the same size can be part of power supplies with different voltages and currents. Use of the wrong power supply may cause severe equipment damage, or even fire.

Common sizes and interchangeability[edit]

Some common DC power connectors

Generic plugs are often described by their inside diameter, such as 2.1mm DC plugs and 2.5mm DC plugs.

After the two common 5.5mm OD plugs, the next-most common size is 3.5mm OD with a 1.3mm ID, usually about 9.5mm in length, although both longer and shorter versions also exist. These 3.5mm OD plugs are normally used for lower voltages and currents.

Locking and retention features[edit]

A ring-shaped 'locking detent' or 'high-retention feature', present on the barrel of some DC coaxial connectors, is a feature intended to prevent accidental disconnection. Typically, this feature is a conical cut-back section of the tip, just behind the insulator that separates the inner from outer contact surfaces.

'lock-ring DC coaxial connector' uses a captive threaded ring or collar to secure the connection between the plug and jack. This design offers strong resistance to unplugging when used properly.

'lock-tab DC coaxial connector' (also called 'bayonet lock') offers a compromise that resists unplugging, but which will disengage when pulled hard enough. This connector uses small metal tab protrusions on the connector barrel to lock the plug in place, requiring a special push-and-rotate motion to engage the locks.


Close-up of a yellow-tipped EIAJ connector. Note 2 round adapter pins on the opposite end.

There are several standards in existence, such as IEC, EIAJ in Japan and DIN in Germany. More recently, some manufacturers appear to have implemented their own system correlating voltage and plug size. In addition, there appears to be a trend to standardize DC connector to negative barrel (or sleeve) of a coaxial power connector.

IEC 60130-10[edit]

IEC 60130-10:1971 defines five DC power connectors.[1]

  • Type A: 5.5 mm OD, 2.1 mm ID (with optional screw lock)
  • Type A: 5.5 mm OD, 2.5 mm ID (with optional screw lock)
  • Type B: 6.0 mm OD, 2.1 mm ID
  • Type B: 6.0 mm OD, 2.5 mm ID
  • Type C: 3.8 mm OD, 1.4 mm ID
  • Type D: 6.3 mm OD, 3.1 mm ID
  • Type E: 3.4 mm OD, 1.3 mm ID

EIAJ power connectors[edit]

For more details on this topic, see EIAJ connector.

Five plug and matching socket or jack designs are defined by the EIAJ standard RC-5320A (also called JEITA RC-5320A). Each of these plugs is used with a specified voltage range. Most manufacturers use a yellow insulating material to distinguish these plugs from other similar-looking DC plugs.

  • EIAJ-01 for 0–3.15 V
  • EIAJ-02 for 3.15–6.3 V
  • EIAJ-03 for 6.3–10.5 V
  • EIAJ-04 for 10.5–13.5 V (also called JSBP 4)
  • EIAJ-05 for 13.5–18 V (also called JSBP 5)

EIAJ-04 and 05 have an internal male pin in the plug. The 01 through 03 sizes do not and are similar to the generic plugs in structure. These five EIAJ plugs are 9.5 mm in length and have a current rating of 2A.

There are two other, less common, connectors defined by EIAJ; RC-5321 and RC-5322. The latter is designed for both 12 V and 24 V automotive applications.

DIN 45323[edit]

The German national standards organization DIN (Deutsches Institut für Normung — German Institute for Standardization) issued DIN 45323, which defines two DC power plug and jack (respectively) sizes. At least one of these sizes has a maximum rating of 34 V and 3 A. The information here is inferred from catalog references,[2] as the German standard has not been translated into English yet.

  • 5.00 mm OD, 2.00 mm ID, 14 mm long?
  • 6.00 mm OD, 1.98 mm ID

Listing of DC coaxial connectors[edit]

This list attempts to show all known sizes, and is annotated with some manufacturers producing selected types, since each manufacturer makes its own unique subset of the known types. Note that the example part numbers given may have different connector barrel (sleeve) lengths, and are not necessarily exact equivalents. There are many more design variants than can be listed in this table, so only a small sampling of part numbers is given.

Connector size is often listed in the format OD (outer diameter) x ID (inner diameter) x L (length of barrel and expressed in millimeters). Designations may vary between manufacturers.

Coaxial plugs that have a male center pin will have another measurement, Center Pin Diameter (CPD). These plugs are often used for higher power applications such as portable computers.

There are a number of sizes listed below that appear to be quite similar, and while the tolerances of these connectors are typically indicated as ±0.05 or ±0.03 mm by the manufacturers, there is still ambiguity as to whether two sizes differing by only 0.05 mm (or where the specification is only given to the nearest 0.10 mm) warrants listing them separately here.[original research?]

OD (mm) ID (mm) CPD (mm) Barrel length (mm) Adaptaplug Standard Volts Plug part numbers Jack part numbers Notes
2.00 0.60               used in newer Nokia phones (AC-3)
2.35 0.70   9.5 A EIAJ-01 0–3.15 V Kobiconn 3218-EX
Lumberg 1636 01
Kobiconn 0307-EX (inline) Canon ACK-800
2.40 0.70           Egston 212   possibly a rounded-off representation of EIAJ-01
2.40 0.80           Egston 213    
2.50 0.75               Used in Samsung Bluetooth headsets and few tablet PCs
3.00 1.00                
3.00 1.10     G     CUI Inc. PP-019
Egston 214
3.20 0.90           CUI Inc. PP-017    
3.40 1.30     H     Kobiconn 3210-E Kobiconn 0309-EX (inline)  
3.40 1.35           Egston 218 Medical, 220    
3.40 1.40           Lumberg NES/J 135    
3.50 0.90             possible nokia acp-7 charger[3] used in many older Nokia phones (ACP-12?)
3.50 1.10           CUI Inc. PP3–002C
Philmore 202
3.50 1.30           Egston 238
Philmore 204,2049
Kobiconn 0308-EX (inline)
Philmore 256 (inline)
3.50 1.35           CUI Inc. P7
CUI Inc. PP3–002D
Egston 215
Kobiconn PA35135-E
3.60 1.15           Egston 216    
3.80 1.10     I     CUI Inc. P9 but with 1.05 mm ID    
3.80 1.30           Egston 217    
3.80 1.35           CUI Inc. P8    
4.00 1.70   9.5 B EIAJ-02 3.15–6.3 V Kobiconn 3219-EX
Lumberg 1636 02
Kobiconn 0311-EX (inline)  
4.75 1.70   9.5 C EIAJ-03 6.3–10.5 V Kobiconn 3220-EX
Lumberg 1636 03
Kobiconn 0310-EX (inline)  
4.75 ?.??   2.5 protruding C EIAJ RC-5321        
5.00 1.50     J          
5.00 2.00       DIN 45323?   Egston 206,207,219    
5.00 2.10     K     CUI Inc. P3    
5.00 2.50     L     CUI Inc. P4    
5.50 1.50     S          
5.50 2.10     M     CUI Inc. P5
CUI Inc. PP3–002A
Kobiconn 3217-EX
Philmore 210, 210L, 2109
Switchcraft S-760, S-765
CUI Inc. PR-002A (inline)
Kobiconn 0302 (inline)
Philmore 257 (inline)
Switchcraft 722A (panel) 
2.1 mm center pin
Common on guitar effect pedals
5.50 2.10           CUI Inc. P10
Kobiconn 7391
Philmore 2560
Switchcraft S760K
  2.1 mm center pin, lock-ring
5.50 2.10           Kobiconn 0721-EX Kobiconn 1000-EX (panel) 2.1 mm center pin, lock-tab
5.50 2.50     N     CUI Inc. P6
CUI Inc. PP3–002B
Egston 222
Kobiconn 0702-EX
Philmore 250, 250L, 2509
Switchcraft 760, 765
CUI Inc. PR-002B (inline)
Kobiconn 0303 (inline)
Philmore 258 (inline)
Switchcraft 712A (panel) 
2.5 mm center pin
5.50 2.50           CUI Inc. P11
Kobiconn 7395
Philmore 2560
Switchcraft 760K
  2.5 mm center pin, lock-ring
5.50 2.50           Kobiconn 0725-EX Kobiconn 1100-EX (panel) 2.5 mm center pin, lock-tab
5.50 2.80     O          
5.50 3.0 5V, 1.5A, Efficiency Level V Philmore Coaxial Power Plug 3.0mm I.D./5.5mm O.D. No. 206 Roku 2 XS HDTV Streaming Box
5.50 3.30 1.00 9.5 D EIAJ-04, JSBP4 10.5–13.5 V Lumberg 1636 04   Microsoft Xbox 360 HD DVD drive
5.50 3.80 1.80   P          
6.00 1.98       DIN 45323   Lumberg 1632 01    
6.30 3.00     Q          
6.50 ?.??       EIAJ RC-5322        
6.50 3.00               Used in Yamaha keyboard power supply
6.50 3.10 1.00         Philmore 285    
6.50 3.40 1.40 9.0     18 VDC @5A Kobiconn 6014-E    used often for laptop computers 
6.50 4.10 1.00   JEITA RC-5322 24 VDC @ 2A Lumberg 1636 06   Epson Photo Scanners V600 etc
6.50 4.30 1.40   T EIAJ-05, JSBP5 13.5–18.0 V Lumberg 1636 05   OD is of ring at tip
6.90 4.20 0.70   R          
7.00 ?? 1.00         Philmore 48-412    
7.4 5.5 0.5 12.5           Some Asus, some Dell, Sony laptops

RadioShack Adaptaplug[edit]

RadioShack sells a line of adapter plugs for universal AC adapters. Each "Adaptaplug" has a single-letter code, but does not provide any other official designation, nor publish the complete specifications and tolerances on barrel and pin dimensions. RadioShack's web site lists the diameters to the nearest 0.1 mm, and sometimes differs slightly from the official EIAJ RC-5320A standard dimensions. This list may include some parts RadioShack has discontinued but are retained here for completeness.[4]

Adaptaplug Outside












Radio Shack

part number

A 2.3 mm 0.7 mm EIAJ-01 < 3.15 V Yellow 3807936
B 4.0 mm 1.7 mm EIAJ-02 3.15 – 6.3 V Yellow 3780266
C 4.7 mm 1.7 mm EIAJ-03 6.3 – 10.5 V Yellow 3780267
D 5.5 mm 3.3 mm 0.9 mm EIAJ-04 10.5 – 13.5 V Yellow 3780268
E 2.5 mm (3/32" submini plug) Black 3870005
F 3.5 mm (1/8" mini plug) Black 3875411
G 3.0 mm 1.1 mm Turquoise 3807935
H 3.4 mm 1.3 mm IEC 60130-10 Type E Orange 3870006
I 3.8 mm 1.1 mm IEC 60130-10 Type C Pink 3870007
J 5.0 mm 1.5 mm Red 3870004
K 5.0 mm 2.1 mm Purple 3807937
L 5.0 mm 2.5 mm Dark Green 3807938
M 5.5 mm 2.1 mm IEC 60130-10 Type A Navy 3807939
N 5.5 mm 2.5 mm IEC 60130-10 Type A White 3807940
O 5.5 mm 2.8 mm Brown 3780269
P 5.5 mm 3.8 mm 1.8 mm Not Specified 3802153
Q 6.3 mm 3.0 mm Yellow-Green 3780270
R 6.9 mm 4.2 mm 0.7 mm Not Specified 3912655
S 5.5 mm 1.5 mm Gray 3875405
T 6.5 mm 4.3 mm 1.4 mm EIAJ-05 13.5 – 18.0 V Yellow 3875406
U 6.5 mm 4.1 mm / 3.10 mm 1.0 mm IEC 60130-10 Type D? Light Yellow 3875407

See also[edit]


External links[edit]

Datasheets (drawings and dimensions)