Power Electronics

Higher Current Demands Drive Power Connector Development

High current connectors used in power delivery systems have been around in different forms and shapes for many years. Primitive nuts-and-bolts style power interfaces used in early commercial computer applications evolved over time into more sophisticated power connectors. OEMs' goals relative to system reliability, serviceability, ease of assembly, and cost were the factors in the development of better power interfaces.

The examples of better interfaces include: pluggable power connectors to help materialize N+1 redundant power systems with replaceable power supply units; board-to-board power connectors to reduce system assembly cost by eliminating the need for cables; and improved contact technologies to meet the need for current interruption under load at the power interface level. Still today, the forces behind power connector design closely relate to the requirements of modern high-reliability, high-availability telecom and computer systems. However, new trends in system design are shaping the power connector development roadmap in a new direction.

As microprocessor voltages head down to the 1V level, current requirements have steadily increased, leading to the need for power connectors with low contact resistance to minimize voltage drop. An increased challenge requires higher current requirements in increasingly smaller form factors. An example of a high-density power connector that meets the contact resistance and size constraints is the MINIPAK (see the Figure). This power connector meets the challenge in a compact package that combines a high-performance Crown Band contact element into a tight contact pitch insulator design. The Crown Band consists of a multifingered design that provides multiple points of contact for better electrical and mechanical characteristics. To address multiple output voltage requirements, the MINIPAK has three contact spacings and an optional dual-pole blade — known as DualBlade — that provides two isolated contacts in the space normally occupied by one. This two-in-one blade allows the designer to obtain the highest current rating per linear inch, with additional output voltages available as needed.

Another trend affecting power connector development is the increased use of bus bar-based power electronic systems. Besides the physical advantages that solid bus bars can have over p. c. board power distribution, laminated bus bars have other benefits, such as low inductance and distributed capacitance with reduced resistance. Although you can mount some cable and board power connectors onto bus bars, there are also bus bar-specific interconnect products that mount and mate with bus bars. One such product is the CROWN CLIP, a true hot plug socket capable of currents up to 350A that mates with a solid bus bar. The most recent iteration of this connector, Dual CROWN CLIP, has a dual-pole contact design to mate specifically with laminated bus bars, extending its benefits to the power interface and providing dual-voltage capabilities in the same space as the original design.

Looking to the future of power connector design, there's a need to reduce the connector inductance of a power delivery system. Lower microprocessor voltages result in higher currents, complicated with increasing response times or current transient requirements. High-speed circuits require lower inductance interconnections to reduce transient spikes to acceptable levels. Because the connector contributes to the total inductance of the power delivery system, limiting the inductance in the order of hundreds of pH is essential to meet this challenge. Early findings by our R&D team indicate that it's possible to produce a low inductance power connector that has high current capabilities and meets the same low-inductance requirements of future systems.

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