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D-Subminiature Connectors Information

D-Subminiature Connectors


D-subminiature or D-sub connectors are sturdy electrical connectors with a mating face shaped like the letter D. The connection has two or more parallel rows of pins or sockets. The pins are surrounded by a metal shield, typically in the shape of a D, which provides mechanical support, ensures correct orientation, and screens against electromagnetic interference. D-sub connectors are considered polarized connectors because they are designed to mate in only one way.




D-subminiature or D-sub connectors are very common and have many applications. The widest application is for RS-232 serial communication. RS-232 is a telecommunication term for a series of standards for serial binary single-ended data and control signals connecting between data terminal equipment (DTE) and data circuit-terminating equipment (DCE), commonly found in computer serial ports. D-sub connectors are used to connect modems, printers, and other peripheral equipment with a computer. The average consumer may recognize these connectors are video output or game controller port connectors. DE9 D-sub connectors are used in some LAN and computer networks



Video Credit: FCI via YouTube


Shell Sizes


To accommodate different arrangements of pins, D-subminiature connectors are available in five standard shell sizes: DA, DB, DC, DD, and DE. The letter represents the shell size and the following number denotes the number of pins. Each shell size usually corresponds to a certain number of pins or sockets: A with 15, B with 25, C with 37, D with 50, and E with 9.
This convention is often followed by a P (plug) or S (socket) - sometimes and M and F are used - to identify the gender of the part. For example a D-sub connector might be marked DB25P. This means that it is a D-sub connector with a 25-position shell size and a 25-position contact configuration. There are some exceptions to this naming convention, such as for personal computer connectors.

D-Subminiature Connectors Naming Chart



D-subminiature connectors image

  • Connector gender is described as either male or female.
    • Male connectors plug into receptacles, jacks, and outlets. They fit securely into the female socket and may have small screws on either side to prevent the connector from disconnecting.
    • Female connectors contain sockets for pins from other devices.
  • The number of pins or sockets in D-subminiature connectors corresponds to the number of wires in the cable. Normal Density spacing of pins is 326/3000 of an inch apart or 0.109 (2.77mm). The rows are spaced 0.112 inches (2.84 mm) apart. The pins in the two rows are offset by half the distance between adjacent contacts in a row (to help with alignment). The contact pitch or distance between pins ranges from as small as 0.0197'' or 0.5 mm to as large as 0.20” or 5.08 mm. High-density and double-density pin arrangements are commonly available.
  • Combination connectors reduce the number of regular pins to accommodate larger coaxial, high current, or high voltage contacts.
  • The voltage rating is the maximum operating voltage for connectors under normal operating conditions.
  • The current rating is the maximum recommended flow of continuous electrical current.
  • Contact resistance is the measurement of electrical resistance of mated contacts when assembled in a connector under typical service use. Electrical resistance is determined by measuring from the rear of the contact area of one contact to the rear of the contact area of its mate (excluding both crimps) while carrying a specified test current. Overall contact resistance would be the wire-to-wire measurement.
  • Insulation resistance measures the electrical resistance between two conductors separated by an insulating material.
  • Operating temperature is the full-required range of ambient operating temperature.

Mounting and Termination


There are several ways to mount and terminate D-subminiature connectors.


Mounting Style


PC Mount


Connectors directly attach to the printed circuit board through pre-drilled holes in the board. Soldering permanently attaches connectors to PCB traces.

Through Hole / Pin

Through-hole technology (THT) mounts components on printed circuit boards by inserting component leads through holes in the board and then soldering. In pin termination, components are mounted on PCBs without soldering.

Surface Mount (SMT)

Surface mount technology (SMT) places small components on the surface of a printed circuit board. Soldering permanently attaches connectors to PCB traces. Unlike PC mount connectors, however, SMT connectors do not require drilled holes in the PCB. Using smaller components allows for higher frequencies of operation, smaller board size, etc.  


Terminals are devices that terminate a conductor. They attach to posts, studs, or other conductors in order to establish an electrical connection. There are several options including:


  • Crimp - Crimp is the physical compression (deformation) of a contact wire barrel around a conductor to make an electrical and mechanical connection to the conductor.
  • Insulation displacement connectors (ICD) - ICD slices through cable insulation to make a connection. Forcing an insulated conductor into a restrictive slot in the connection part of the contact displaces the insulation so that the bare wire engages the sides of the slot. IDCs are mass termination connectors for flat cables and eliminate the need to strip insulation.
  • Solder cup or solder - Solder cups are terminal ends or contacts into which conductors are inserted before soldering. A metal or metallic alloy is used to join metal surfaces together. Normally, a 60-40 rosin core (60% tin and 40% lead) is used for soldering electronic assemblies. Soldering is a wet process.
  • Wire wrap - Electrical connections are made by wrapping a stripped or unstripped solid wire around a terminal post that contains a series of sharp edges. This solderless process requires a special wrapping tool.

Video Credit: AmphenoILTW / CC BT-SA 4.0





D-subminiature connectors are available with a variety of special features.


Integrated Filter / Magnetics -

The connector has a filter to protect it against unwanted signals, or magnetics to provide filtering, signal conditioning or isolation.

Underwater Use -

The connector can be used in underwater applications.

Water Resistant Connector -

A connector capable of being permanently used under water.

Cryogenic Use -

The connector can be used in a cryogenic (subfreezing) environment.

EMI or RFI Filter / ESD Shield -

The connector has a filter to eliminate electromagnetic interference (EMI), radio frequency interference (RFI), and/or shielding to prevent electrostatic discharge (ESD) or EMI.

Environment Resistant-

The connector can be used in a hazardous chemical environment.


Custom D-subminiature connectors are often available.




D-sub connectors


Image Credits:

Black Box | Computer Desktop EncyclopediaNorthern Connectors




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