What are the specifications of commonly used power adapter DC plugs?

Circular connector

The shape of the circular DC head is a hollow cylinder, which is generally positive and negative inside and outside.The outer part of the cylinder is a metal part.The middle is a plastic insulation part. It is a tuning fork DC head, and the inner wall is a piece of metal.The inner wall is a straight plug DC head.

The DC tuning fork head and the DC straight plug belong to one of the DC plugs of the power adapter. Their outer diameters are the same, and there is no difference. The difference is that there are two corresponding metal shrapnel on the inner wall of the tuning fork DC head on the inner wall. There are two spring pieces on the inner wall of the DC head for contact connection with the metal inner pin of the DC seat.The main reason is that the insertion force can be used with different spring pieces according to the user's needs.The purpose is to make the plug contact and stability are better. Because the inside is a spring leaf contact, the matching DC seat inner pin is required to be slightly looser in size.For example, the 5.5*2.5 tuning fork plug can be matched with the socket matching 5.5*2.5 or the socket matching 5.5*2.1 However, if the two springs on the inner wall of the DC head have insufficient elasticity, they will definitely contact poorly.

There is no shrapnel in the inner wall of the DC plug, and the entire inner wall is a smooth metal cylinder. The matching DC seat inner pin contact connection is not as good as the stability of the tuning fork plug. But in the case of high current It is more stable to use, because the contact area between the inner wall of the DC plug and the metal inner pin of the DC seat is larger than the DC head of the tuning fork. It has stricter requirements on the size of the metal inner pin of the DC seat. For example, 5.5*2.5 tuning fork plug can only be compatible with 5.5*2.5. Matching socket matching, if it matches with 5.5*2.1 matching socket, it will not be able to match contact or poor contact occurs.

According to different inner and outer diameters, it is divided into many middle specifications. The common ones are 5.5*2.1/5.5*2.5/3.5*1.35 and other specifications. The circular interface DC head is the most common in our daily life. The current commonly used circular interface DC specifications There are the following:

(1) 2.5*0.7 (outer diameter * inner diameter), mainly used for small electronic products with relatively limited volume such as tablet computers.At present, tablet computers are charged with Micro USB or Type-C USB.

(2) 3.5*1.35 (outer diameter * inner diameter), mainly used for network set-top boxes, USB HUB external Power Supply, IPcamera (that is, network camera is also known as shaking head machine), LED desk lamp.

(3) 4.0*1.7 (outer diameter*inner diameter), mainly used for mobile DVD, EVD, PSP, some network set-top boxes and smart speakers.

(4) 5.5*2.1 (outer diameter * inner diameter), currently the most widely used DC round head interface, surveillance cameras, some set-top boxes, LED table lamps, digital home appliances and other electronic products.

(5) 5.5*2.5 (outer diameter * inner diameter), mainly used for equipment with a slightly larger power, such as some notebook computers, electric vehicles, etc.