High-Reliability Rad-Hard DC-DC Converter

Alphacore (AC) will develop an innovative radiation-hard high-reliability DC-to-DC converter for future Exoatmospheric Kill Vehicle and other radiation applications. The Phase II prototype takes a spacecraft’s bus voltage or battery pack voltage (24V up to 34 V) as an input and produces an isolated or a non-isolated output as low as 900 mV, with a fully programmable output voltage. The solution is optimal for space-based apps due its radiation hardness and capability of operating under low size, weight, and power (SWaP) restrictions. This proposal addresses both circuit design and environmental challenges of the envisioned solution. The new design is application-driven and is meant to be an excellent fit for high-reliability, high-radiation tolerance levels applications such as the constellation satellites for missile defense, situational awareness and exploration. Alphacore’s solution has a total ionizing dose (TID) of >1MRad (Si), and can be modified for various voltages and power outputs, benefitting applications such as spacesuits, nanosatellites and space-based robotics and electronics. AC has found a critical need for rad hard space-qualified converters that can directly convert voltages from 24V–34V down to 1V, and while supporting up to 20A of peak-current to the load, with nominal output current of 10A. To increase the commercialization potential AC 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 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 counterparts, SIMO converters also employ negative feedback to define and control their outputs. The high-current DC-DC converter specs are possible with a hybrid CMOS controller/driver+GaN power stage architecture. The proposed hybrid DC-DC converter platform will have a fully integrated GaN driver stage with its own bootstrapped power supply, minimizing the overall component count and PCB area, and solid radiation hardening. The controller will be based on Constant-on-Time control, and the topology will allow both isolated and non-isolated buck topology. Note that Alphacore will also investigate the specifications achievable with a System-in-a-Package solution in this program. With this approach, the proposed power converter will achieve two main power distribution systems and multiple functions at the same time, namely, both isolated Intermediate Bus Converter, Distributed Bus Architecture, and non-isolated POL functionality included into a single converter controller, with an additional benefit of multiple output regulation. Approved for Public Release | 22-MDA-11102 (22 Mar 22)