The design goal of the power management subsystem in the Aerospace/Defense applications is the precision control of a voltage level or levels within a defined topology. Additionally, constraints on package size often require custom tooled components such as potting shells, headers and bobbins. This increases the level of complexity and attention to detail required during construction and often leads to reliance on workmanship which is often difficult to account for in the written documentation. As a result, DFM (designing for manufacturability) is too often compromised for reduced board space. What follows in cases such as these are repeated production yield variances and the consumption of QA resources. DFM focuses on the elimination of process variables that are often deemed acceptable by transformer designers and manufacturers, both commercial and captive.
     Utilizing Finite Element Analysis and Spice Circuit Simulations allows one to redefine core geometry and improve DFM. Another critical factor designers often overlook pertains to MTBF and related test methods. Most transformer manufacturers look only at a single dielectric strength go/no go test as a means for assessing long term reliability. Corona (partial discharge) abatement at elevated system voltages, along with designing for overall system BIL requirements will increase the certainty factor in MTBF calculations as well as increasing overall MTBF. This is especially true if the platform is exposed to lightning strikes or grid / power source perturbations.
     The nine main types of components that are used in these applications are switch mode, feed forward, flyback, inverter, buck/boost, isolation, step up, step down. BIL and / or Corona Free ratings of these devices will have a direct impact on reliability, MTBF, and related warranties.

Primary Design Considerations Summary
• Design for Manufacturability
• System stability and the impact on power regulation
• Reliability/MTBF as impacted by voltage surges (especially in airborne platforms where susceptibility to lightning strikes is high)
• Power density and Efficiency
• MTBF
• Grid/Power Source Perturbations
• Corona abatement
• BIL