D-subminiature Connectors

D-subminiature or D-sub connectors are sturdy electrical connectors with a mating face shaped like the letter D. They provide polarization because male and female connectors can fit together in only one way. Male connectors plug into receptacles, jacks, and outlets. 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. To accommodate different arrangements of pins, D-subminiature connectors are available in five standard shell sizes: DA, DB, DC, DD, and DE. 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.

There are several ways to mount and terminate D-subminiature connectors. PC-mounted and through-hole connectors are inserted into pre-drilled holes in printed circuit boards (PCBs) and then soldered into place. With pin termination, components are attached to PCBs but not soldered. Surface mount technology (SMT) solders components to the surface of PCBs. In terms of termination options, crimping compresses or deforms a contact wire barrel around a conductor. Wire wrapping requires the use of a special tool to wrap a stripped or unstripped wire around a terminal post that contains a series of sharp edges. With flat ribbon cables, insulation displacement connectors (IDCs) are used to slice through cable insulation. Forcing an insulated conductor into a restrictive slot displaces the insulation, allowing the bare wire to engage the sides of the slot. 

Performance specifications for D-subminiature connectors include voltage rating, current rating, contact resistance, insulation resistance, and number of 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 measures the electrical resistance of mated contacts. Insulation resistance measures the electrical resistance between two conductors separated by an insulating material. Typically, electrical resistance is determined by measuring from the rear of the contact area for one contact to the rear of the contact area of its mate while carrying a specified test current. 

D-subminiature connectors are available with a variety of special features. Some connectors include filters that remove unwanted signals and magnetics for signal conditioning and isolation. Other connectors filter electromagnetic interference (EMI) and radio frequency interference (RFI), and/or provide shielding that prevents electrostatic discharge (ESD). Cryogenic connectors can be used in extremely cold environments. Waterproof connectors are designed for continuous underwater use. Environmentally resistant connectors can be used in hazardous environments such as chemical processing facilities. Custom D-subminiature connectors are often available.

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