COVER STORY
Open-standard VPX is gaining momentum in the US, Europe, and beyond
With so much uniformity, how can you discern the best power supply for your program? By Dan Morgan, President of Freedom Power, a Vicor Company
S
ince 2010, the VITA (OpenVPX) and the Sensor Open Systems Architecture (SOSA) standards have been a strategic boon for U.S. defence. By standardizing form factors, backplane interfaces, and power rails for rack-based embedded computing, these architectures have opened the defence electronics supply chain to multi-vendor competition for the first time.
Now, what began as a U.S. program initiative is gaining traction well beyond American borders. Today, European defence primes, allied nations, and global contractors worldwide all specify 3U and 6U VPX power cards for airborne, ground vehicle, and electronic warfare systems, using the U.S.-developed SOSA baseline as their starting point. And, the supplier ecosystem has grown to match, with multiple vendors now offering SOSA-aligned power cards that drop into any chassis.
With so many vendors offering interoperable solutions, it can be hard for designers to know which product best fits their given design requirements. To make better, more informed defence electronics decisions, designers need to first understand which specifications to look for and what trade- offs will be acceptable.
Challenges in an open-standards market Prior to VITA and SOSA, defence electronics historically relied on bespoke, single-vendor designs. In these instances, engineers built each program’s power subsystem to that platform’s specific requirements, sourced it from a single supplier, and qualified it once. While that arrangement provided predictability, the acute specificity hindered competition.
The U.S. developed VITA and SOSA to change that narrative through standardization (Figure 1). Specifically, these architectures standardize form factors, backplane pinouts, and power interfaces to enable inter-vendor interoperability between otherwise disparate defence systems. For example, a SOSA-aligned VPX power card accepts 28 or 270 V input and delivers a 12 V high-current output with a 3.3 V auxiliary rail, packaged in a 3U or 6U form factor for any chassis. In that way, defence designers get the confidence and security they need, knowing that any two vendors’ cards will slot into the same backplane and output the same voltages.
But even though standardization guarantees conformity with respect to form factor, input, and output, not all solutions are equal. In reality, many other considerations – such as internal
10 May 2026 Components in Electronics
Figure 1: Vicor VITA 62 and SOSA power supplies classified by input voltages – a system of standardization that has enabled multi-vendor competition.
topology, qualification rigor, power-density headroom, and supplier reliability – should all factor into a designer’s choice of VITA and SOSA-aligned solutions.
Standards such as MIL-STD-461, MIL-STD-1275, and MIL- STD-704 set electrical requirements for defence power electronics. And while nearly every VPX power card datasheet references these standards, suppliers normally designate their solutions as either “designed to meet” or “qualified to” a given standard.
A “designed to meet” means the standards are the target, but the designers have not necessarily completed testing or formally documented results. For instance, a card labelled “designed to meet MIL-STD-461” has not necessarily passed EMC testing.
“Qualified to”, on the other hand, means the designers have run the product through the full test regimen and hold documented results. Designers know for certain that a card qualified to MIL-STD-461 has completed testing with traceable, accessible data to prove it.
The difference matters because discovering compliance failures during system integration testing can derail schedules and budgets. “Qualified to” solutions give designers much higher confidence in success and compliance, whereas “designed to” solutions are more likely to require late-stage redesigns that restart full qualification campaigns, which can take months and cost millions.
This difference is even more pronounced in Europe, where defence customers routinely request compliance documentation
before contract award. A supplier that can provide complete qualification test reports on first request can shorten the evaluation cycle and remove a source of program risk before the program begins.
Consideration 2: Modular internal architecture At the highest level, SOSA specifies the power card’s output interface (i.e., the voltages delivered, the connector pinout, and the form factor). But the standard says nothing about how the card generates that output. Two cards that both satisfy the SOSA power interface specification can be built around entirely different internal architectures, with very different implications for program flexibility. For example, a card built around discrete, hard-switched converters is likely one optimized for a single design point. The designers have already tuned the magnetic components, switching network, and control loop to specific input and output conditions. Any request for non- standard auxiliary voltages, split rails, or unusual transient profiles would then require a full board redesign, which in turn restarts the entire qualification process. In contrast, with a card built on modular DC-DC converters, designers can handle non-standard outputs by simply reconfiguring or swapping internal modules as shown in Figure 2. In such a situation, they can keep the front-end compliance circuitry, EMI filtering, and primary conversion stage identical while only changing the output stage. As a result, only the output stage would require re-evaluation, while the rest of the card can carry forward. Comparatively, this approach yields a significantly more flexible design that, in turn, can save organizations significant time and money later on.
www.cieonline.co.uk
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