Design engineers have traditionally treated power supplies as an afterthought. For years there was enough margin in power and cooling systems to let users continue this practice. Today, higher circuit speeds and density translate into higher power densities and, many times, the need for multiple power supplies. The problem of power quantity and quality leads to concerns over reliability, heat, system real estate for power conversion, and electromagnetic-interference (EMI) compliance.
These demands will intensify as engineers strive to achieve seemingly impossible improvements in system speed, reduction in rack space, higher-power devices, and higher reliability. These battles will be played out in several arenas, resulting in changes in power-supply requirements, implementation methods, and standards committee specifications. For example, new bus standards are calling for a common 48-V distributed power scheme, such as PICMG 3.0. Meanwhile, existing CompactPCI, VME64x boards use centralized +5-V, +3-V, +12-V, and 12-V supplies.
Requirements for power supplies are changing dramatically, forcing power designers to use smaller, more efficient solutions. Great importance is attached to physical size, efficiency, maintainability, reliability, and scalability, as well as the supply's ability to satisfy stringent environmental requirements. As performance verification becomes even more critical, the use of intelligent, real-time monitoring, which today is just an added "bell and whistle" in many packaged systems, will become a necessity. Real-time monitoring gives early warning of out-of-tolerance operation, faulty connectors, and other latent problems before they become critical. At the same time, increasing sophistication in undervoltage and overvoltage protection, current limiting, and thermal shutdown provides multiple levels of power-supply and load protection.
DESIGNS TO LOOK FOR:
> Improved air flow via lower parts count and better placement of output cables or bus bars.
> Plug-in modules eliminate power cables, improving response to transient loads.
> Configurability and commonality allow outputs to be turned on or off, paralleled, remote sensed, voltage- and current-limit adjusted, temperature- and current-monitored.
Even with all of these improvements and a tighter focus on power needs at the beginning of a design project, the ability to meet system requirements in the current arena of tightly integrated telecom, data acquisition, aerospace, and related systems in an optimal way frequently falls short. Future system designs must increasingly adopt a "simultaneous solution" approach to addressing packaging, backplane, thermal, power, and integration needs. This technique led to the development of the single-slot, high-efficiency power supplies now coming to market.
As power densities continue to increase and systems become more sophisticated—with the common theme of smaller, faster, and more reliable—custom solutions will rapidly migrate into standard power-supply products.
Supplies will offer high density and exhibit excellent dynamic response and load regulation. In addition, they'll provide enhanced system control with configurable set points for power failure, derating, overvoltage, overcurrent trip, etc., plus microprocessor control and an I2C bus for monitoring and control. Also, common system cooling will eliminate the need for separate air filters or fan monitoring.
Power solutions over the next few years will follow the "simultaneous solution" path being taken for backplane design, thermal management, and with all phases of packaged system design for critical applications. Rather than viewing basic design tasks as isolated steps, design engineers will need to view the entire chassis as a complete system and design all components at once to achieve the increasingly demanding specifications required by future systems.