Omnetics’ director of technology looks at the big demands on designs for small and portable devices and how trends in electronics affect connector development.
Rapidly changing requirements for product performance and electrical integrity have a significant effect on electronic connector systems. To meet the needs of the new smaller and more-portable electronics in aerospace, defense, and other stressful environments (like those encountered in robotics and oil exploration), changes are needed in standard micro-D connectors. New technology, including latching micro-D connectors, offer significant improvements for rapid connection and release with proven signal integrity for the portable and ruggedized electronics flooding into the market. The new latch technology provides excellent performance in high shock and vibration environments when tested at military-level specifications.
Instruments are changing rapidly and everything is getting smaller. Today’s newer electronic modules can afford neither the space nor the weight required by older cabling and connector systems. Figure 1 shows some of the variety of connector types traditionally used for electronics.
Smaller and Lighter Connectors
Many of the older military specification models are rapidly becoming outdated in the face of the evolving demand for smaller and lighter connection systems. Older connectors, like the D-subminiature connectors (MIL-DTL-24308) that require 0.100″ from pin to pin, just don’t fit within today’s systems. Rapid industry growth in micro-size connectors with 0.050″ spacing and nano connectors at 0.025″ spacing are fulfilling the need in today’s higher technology electronics. For example, a number of military and deep space applications began using robotics, and soon we began to see emergency rescue device development companies using miniature cables and connectors, too. Then, since many emergency applications require the use of devices that can run at higher temperatures, up to 200°C, we began to see the petroleum research and geothermal industry follow suit, testing new micro-D connector technology for their applications.
In short, squeezing a lot of technology into small spaces is becoming key across the industry, and micro-D connector technology must meet that need. The designers are heralding the ruggedized miniature connector as a major solution to a number of design needs and application-related demands. The trend also includes a need for quick plug-and-release connector technology, because users do not want to have to go back to a lab and use additional tools to mate or release a connector.
Increasing Complexity of Electronic Circuitry
As electrical circuit technology and complexity evolves, chip speeds are increasing their data processing rates, current and voltages are being used at lower levels, and mixed signal systems are demanded within the same interconnect system. The use of these new circuits with higher and higher circuit speeds are most critical in surveillance cameras and high-resolution displays used in portable military applications, space satellites, and ruggedized robotic equipment.
Miniature systems are moved from the big box out through cabling to probes and sensors to deliver a variety of information to the main unit. Circuits in mission-critical applications are often placed in harm’s way and must retain the highest reliability and maintain signal integrity even in stressful environments, including high shock and constant vibration of the electronics.
Changes in the applications have demanded evolution in the connection from each electronic module to the main driving instrument. A number of critical elements have changed in both the application and the design of those interconnection systems that serve the new electronics:
- Voltages are somewhat standardized and are lower.
- Current levels are dropping to the milliamp levels.
- Space for signal routing is limited.
- Weight of the connector and cable must be reduced.
- Ruggedness is increasingly significant.
- Rapid mating is often critical in field applications.
Industry trends have shown that most cable and connector manufacturers are rapidly tooling smaller interconnect systems to meet the new mechanical and physical configurations that serve ruggedized miniature electronics. Electronic design groups are also pushing new limits in providing faster and more efficient microchips. Expanded C-MOS technologies have combined most electronic sub-systems within one-chip design. These new chips offer higher speeds, larger memory sections, and operate on lower voltages and lower current.
Analog vs. Digital Signal Processing
Analog signal management is giving way to digital signal processing. Analog signals are not going away and remain useful in certain level-sense control and modulation circuits, but they often require larger wire diameters and higher voltages.
Digital processing seems to be eclipsing many design areas from commercial communication, like cellular phones, to high-level military and space technology. The digital signal method can be routed easily and sped up with lower costs.
Many cables use a differential pair of twisted wires, such as Apple’s FireWire design. Highly reliable signal speeds are being achieved and maintain high signal integrity as they perform in the Gigahertz range on extremely small-diameter wire. This trend allows the placement of new, unique electronic products in portable and rugged applications. It is also important to note that digital signal processing inside shielded cabling can be more secure than those using signal transmission through the airwaves.
Proven Designs Combined with New Trends
Micro-D connector technology has been around for generations. Now we also have the new latching micro-D designs offered by at least two manufacturers. The advantage of this technology is that it meets the requirements of smaller and more mobile technologies. These technologies tend to require more frequent module changes and rapid field replacement of systems in places where additional tools may not be available. Digital signals from optical surveillance systems, low-voltage differential signals, and even lower-current power supplies are some of the newer applications taking advantage of the quick-change design opportunities of the new latching micro-D connection systems (Figure 2).
The new technology is based on the micro-D’s well-established reliability and performance specifications. It also takes advantage of its predictable voltage and current ratings and the fact that it is adaptable for many board-mount, panel-mount, and wiring configurations and pin counts. With the latch design, the cable can be quickly disconnected in a simple squeeze-and-pull motion. An adapter can be added to existing micro-D connectors to allow current instruments to use the latch on cables in their system. Omnetics Connector Corp., for example, has built and proven testing to pass the Military Standard 83513 specifications to assure high reliability performance in the future of portable miniature electronics.
Bob Stanton is director of technology at Omnetics.