Maintain Power Integrity and Flexibility Using D-Subminiature Connectors with 75 A Current Ratings

Power requirements in electronics are increasing across applications that include electric vehicles (EVs) and industrial and telecommunications systems, all of which demand robust and reliable connectors. This is particularly true for power distribution. Designers need high-power connectors that offer flexibility in the number of positions, contact configurations, and terminations while maintaining high power integrity.

The D-subminiature (D-sub) connector is perhaps the most popular multipin connector in electronics and meets many of the requirements of power systems. It is available in various configurations and fits thousands of applications. As power demands increase, the D-sub needs to evolve accordingly if designers are to meet their customers’ needs.

This article briefly describes the D-sub connector. It then introduces a high-power solution from Amphenol ICC and shows how it can be applied.

How D-sub connectors got their name

D-sub connectors are basic connectors used widely in various applications across the data communications, military, consumer, industrial, instrumentation, and medical fields. Their name derives from the D shape of the connector shells (Figure 1). This distinctive shape makes it self-keying to prevent improper insertion and guarantee a secure connection.

Figure 1: The D shape of a D-sub connector shell provides keying to prevent improper mating while guaranteeing secure mechanical and electrical connection. (Image source: Amphenol ICC)

D-sub connectors have two genders: parts with pin contacts are called plugs, while those with socket contacts are called sockets. The socket's shield fits tightly inside the plug's shield. The exterior shells provide mechanical strength and electrical continuity, which protects against electromagnetic interference (EMI). A variety of hardware mounting options ensure a secure connection.

Protective hoods for strain relief on cables are available in plastic, metalized, or metallic materials. Metal and metalized hoods contact the shielded cable's shield braid to reduce EMI further. The hoods offer straight or angled exit ports and include various locking options.

D-sub high-power connectors

Amphenol ICC offers a wide range of D-sub connectors in standard and high-density form factors. To meet the increasing power needs of many applications, it has added a series of high-power D-sub connectors with 75 ampere (A) power contacts. Connectors in this series have contact layouts with two, three, five, or eight power contacts (Figure 2).

Figure 2: The contact layouts for the Amphenol D-sub, high-power series connectors offer two, three, five, or eight contacts. (Image source: Amphenol ICC)

The layouts designated with a W in Figure 2, such as 5W5, indicate that the power contacts all lie in the same plane in the connector body. Those designated with a V indicate that one of the contacts is depressed into the connector body for sockets and extended beyond the body for plugs. One contact is engaged before the others, allowing ground or another source to be engaged before the other pins make contact. Contacts in the W-style layouts are connected simultaneously when the plug and socket connectors are engaged.

The D-sub connector’s shell sizes are A, B, C, D, and E. These are historic labels based on the original D connector pin layouts. The A shell has 15 standard pins, B has 25, C has 37, D has 50, and E has 9. The D-sub high-power connectors use larger pins and incorporate proportionally fewer pins in any given shell size.

The Amphenol D-sub high-power connectors deliver their 75 A per contact at a maximum voltage of 300 volts. The mated contacts have a series resistance of less than 7.3 milliohms (mΩ). The resistance represents a less than 0.55 volt drop across the contacts at 75 A. The current rating is based on UL 1977, “Component Connectors for Use in Data, Signal, Control, and Power Applications.” The test itself is based on the temperature of the connector at rated load: “The temperature of a device, when measured at the test points, shall not exceed the Relative Thermal Index (+130°C) of the insulating material” when the device is carrying its maximum rated current of 75 A.

The Relative Thermal Index (RTI) is the maximum service temperature at which the critical properties of a material will remain within acceptable limits over an extended period. A typical 8W8 eight-contact configured connector exhibits a 75°C temperature rise with a 75 A current (Figure 3).

Figure 3: Shown is the measured temperature rise of an 8W8 high-power connector at 75 A. (Image source: Amphenol ICC)

The connectors are rated to operate over a temperature range of -55°C to +125°C. The maximum current specification assumes the connector is at ambient room temperature and is derated based on its actual temperature (Figure 4).

Figure 4: Shown is an example of a typical temperature derating curve for an 8W8 connector with soldered contacts. (Image source: Amphenol ICC)

The Amphenol ICC D-sub high-power connector contacts are available in solder bucket, crimp, and right-angle versions to support printed circuit board, panel, and cable mounting requirements.

Typical high-power connector configurations

The Amphenol ICC DA3W3PA009KLF is a three-position plug housing mounted in an A shell. It accepts plug contacts such as the 8638PPC7506LF pin, a machined contact pin with a crimp connection. This type of connection is used in a cable-mounted connector. An alternative contact is the 8638PPS7506LF, a machined plug with a solder cup contract termination.

Another version of the 3W3 housing is the DA3W3SA009KLF. It takes a socket contact like the machined 8638PSC7506LF with crimp termination. Various plug and socket contacts with crimp and solder cup terminations are available.

The Amphenol ICC DBV5W5P500H9KLF is an example of a right-angle connector intended for printed circuit board (pc board) mounting. It is a 5W5 five-contact plug connector, which includes the plug contacts (Figure 5).

Figure 5: The DBV5W5P500H9KLF is a 5W5 five-contact plug connector for pc board mounting with integral plug contacts. (Image source: Amphenol ICC)

The connectors offer a variety of pc board and panel mounting accessories to ensure secure locking of the connector bodies. The front accessories include threaded inserts or female screws with either M3 or UNC 4-4 threading. Board-mount accessories include metal brackets and harpoons (Figure 6).

Figure 6: Various mounting accessories can be used to secure the connectors to a pc board. (Image source: Amphenol ICC)

The 5W5 plug, shown in Figure 5, includes harpoons for mounting to the pc board and female screws to lock in the mating connector. The right-angle connectors' mating socket and two, three, and eight-contact versions are also available.

D-sub high-power applications

Example applications for the high-power D-sub series include Industry 4.0, where they can supply power to industrial computers. Unlike typical desktop computers, these embedded computers are designed to operate in harsh environments. They are exposed to shock, vibration, and wide temperature variations. The high-power connectors offer reliable connections with flexible contact configurations. Similarly, these connectors can power programmable logic controllers (PLCs) and other machine automation electronics.

Conclusion

The Amphenol ICC D-sub high-power connectors extend the applications range of the venerable D connector by adding reliable power connections with a maximum current rating of 75 A on up to eight lines.