Statistics from the past 50 years reveal that commercial air travel has become one of the safest, most reliable forms of transportation. As the safety of commercial flight continues to increase, the demand for advanced commercial avionics technologies continues to grow. In September 2014, Avascent projected the global market for commercial avionics equipment will grow at a rate of 4.8 percent through 2019. The firm also estimated $21 billion will be spent on commercial avionics systems for fixed-wing commercial aircraft in 2015.
In terms of financial value, Lucintel analysts ranked the largest segments in commercial avionics, beginning with the largest:
1. Communication network and navigation
2. Control systems
3. Radar and surveillance
4. Display systems
In addition to the systems listed above, examples of advanced commercial avionics include steering systems, airplane sensors, landing aid systems, infotainment, advanced warning technology, upgraded cockpits with LED displays, sophisticated weather data collectors that detect severe turbulence or wind shear, and flight recorders that analyze common problems. Advanced tracking and recording technologies enable regulators, pilots, and airlines to share extensive information about flying hazards, enhancing the reliability and safety of commercial air travel.
Increased complexity leads to increased vulnerability
As with most electronics systems, the expansion of commercial avionics and the increasing complexity leads to increased vulnerabilities and risks. Adding advanced avionics means creating more hidden, complex electrical systems in the aircraft. The more working parts in the avionics system, the more susceptible the electronics are to damage.
Avionics systems are subjected to a variety of hazardous conditions, including extreme pressures and temperatures, lightning surges, electrostatic discharge (ESD), and other transients. Electrical systems located in difficult to reach hidden panels could be damaged by over-voltage transients that render them useless or faulty. An avionics system failure could lead to expensive repairs or require equipment replacement. Worst case scenario, a failure could jeopardize the lives of crew members and passengers.
High-reliability circuit protection
High-reliability circuit protection is the key to safeguarding the sensitive electronics in advanced commercial avionics from a catastrophic event. With the right circuit protection solution, hard-to-access electrical systems can operate with increased safety and dependability.
Today’s design engineers rely on transient voltage suppression (TVS) diodes to protect commercial avionics. TVS diodes provide DC power protection and ESD protection in aviation electronics like full authority digital engine control (FADEC) systems, airplane sensors, avionics computers, fly-by-wire flight control systems, cockpit electronic equipment, and airport landing aid systems. These silicon avalanche devices are chosen for the fast response time, low clamping voltage, high surge capability, and low leakage current. They are designed to protect sensitive electronic equipment from voltage transients induced by lightning surges, ESD and other transients.
Tips for selecting a manufacturer
To find the best circuit protection solution for an avionics application, the design engineer must first identify a reliable manufacturer of circuit protection devices. Here are the top characteristics to look for in a TVS diode manufacturer:
• Specialized expertise in TVS diodes for critical applications
• History use in the aerospace industry with market-proven results.
• Flexibility in production capability for high volume, growing demand.
• Testing and proving services for design and compliance support.
• A broad range of circuit protection products and solutions.
• A global delivery network.
Must-have features
Once the manufacturer has been identified, the design engineer should consider the features of the TVS diodes from the company’s product portfolio. The most important feature is the upscreening and sorting process used to ensure that only the TVS diodes that meet the MIL-STD and JEDEC standards are selected. This highly precise process ensures exceptional reliability and performance of the devices. In addition to the screening and sorting, surge testing, high-temperature reverse bias (HTRB) testing, and electrical test sorting should be available.
For flexibility, the TVS diode should be produced with one of two options: off-the-shelf upscreening and Group B test stresses, including surge immunity, burn-in (i.e., HTRB), etc., or customized upscreening and sorting process flows dictated by the manufacturer’s internal requirements. Ideal TVS diodes come in compact SMB, SMC, and SMD DO-214AA packages and are rated between 600 W and 3,000 W of peak pulse power dissipation. They should also allow for easy design-in compliant with the RTCA/DO-160 standard for environmental conditions and test procedures for airborne equipment.
As the commercial avionics industry continues to advance in safety and reliability, the demand for complex avionics continues to grow. With the growth of advanced avionics comes the demand for circuit protection technologies to protect the sensitive electrical components within these complex systems.
Proper circuit protection using TVS diode technology ensures the safety and integrity of the aircraft electronics and protects the lives of the crew and passengers.
