High-Reliability Rad-Hard DC-DC Converter

In response to Department of Defense SBIR topic MDA20-006, Alphacore Inc. will develop an innovative radiation-hard high-reliability DC-to-DC converter for future space-based missile defense applications. The Phase II prototype takes a spacecraft’s bus voltage (up to 28 V) as an input and produces an isolated output of 3.3 – 5V. This capability is required to power modern space electronics, such as field programmable gate arrays (FPGAs). The solution is optimal for space-based applications due its radiation hardness and capability of operating under low SWaP restrictions. This proposal addresses both circuit design and environmental challenges of the envisioned solution. Alphacore has found a critical need for space-qualified converters that can directly convert voltages from 18V – 28V satellite bus voltages down to 3.3V, and even all the way to 900mV, while supporting up to 20A of current to the load, which is the current draw requirement of the newest, high-performance FPGAs, which are very attractive devices for numerous space applications. The high-current DC-DC converter specifications are possible with a hybrid CMOS controller/driver + GaN power stage architecture. Note that Alphacore will also investigate the specifications achievable with a fully monolithic solution in this program. With this approach, the proposed power converter will achieve two functions at the same time, namely, both isolated Intermediate Bus Converter (IBC) and POL functionality into a single converter, with an additional benefit of multiple output regulation. To increase the commercialization potential Alphacore is planning to add a very desirable capability to the converter, namely isolated multiple output capability. There is an increasing need of DC-DC converters capable to generate many outputs while using a single inductor or transformer. Multiple supply levels requiring increased PCB area, increased number of external components, and the reduced reliability for the many inductors used, become problematic. Single-inductor, multiple-output (SIMO) switching DC-DC converters offer advantages in the form of high efficiency and small form factor, but with associated challenges. As in their single-inductor single-output (SISO) counterparts, SIMO converters also employ negative feedback to define and control their outputs. Feedback control must therefore be stable and sufficiently fast to accurately regulate the outputs against sudden changes in load power and line voltage. Unlike SISO converters, however, variations in individual outputs may affect the others because they all share one common inductor. Approved for Public Release | 20-MDA-10643 (3 Dec 20)