EPC Space targets processor rails with rad-hard GaN

EPC Space has introduced three low-voltage radiation-hardened enhancement-mode gallium nitride transistors for high-current power conversion around processors and accelerators used in spacecraft. The EPC7050PCSH, EPC7066PCSH, and EPC7065PCSH cover 15 V, 25 V, and 40 V ratings respectively, with each device specified for 101 A continuous current.

The voltage range places the family on the secondary and point-of-load side of a spacecraft power architecture rather than directly on a high-voltage primary bus. EPC Space is targeting synchronous rectification on intermediate bus converters producing rails in the 5 V to 12 V range, together with point-of-load and integrated voltage regulation supplying processor cores at around 0.8 V.

Typical on-resistance is quoted at 0.28 mΩ for the 15 V device, 0.37 mΩ for the 25 V part, and 0.5 mΩ for the 40 V version. At currents approaching 100 A, those fractions of a milliohm translate directly into heat that the board and package have to remove, so conduction loss becomes an architectural issue rather than a minor component specification.

The devices are supplied in compact plastic PQFN packages with backside thermal pads. EPC Space also specifies zero reverse-recovery charge, a characteristic of GaN devices that is attractive in high-frequency synchronous conversion because it removes the reverse-recovery loss associated with a conventional body diode. Faster switching can reduce magnetics and energy-storage component size, although layout inductance, gate drive, ringing, and electromagnetic compatibility become progressively less forgiving as edge rates increase.

Radiation performance is the additional constraint for space use. EPC Space’s launch release states total ionising dose immunity above 1 Mrad, neutron exposure above 4 × 10^15 n/cm², and single-event effect immunity at LET(Si) 85 MeV cm²/mg for the three-device family. The current product page for the 40 V EPC7065PCSH lists 83.2 MeV/(mg/cm²) for its SEE figure, however, so designers qualifying that part will need to work from the controlled datasheet and screening documentation rather than rely on the rounded family figure in the announcement.

That sort of detail matters because radiation-hard component selection is based on the conditions under which a result was obtained, not simply on a marketing label. Total ionising dose, single-event effects, neutron exposure, bias conditions, temperature, lot screening, and the applied derating policy can all affect whether a device is suitable for a particular mission. EPC Space distinguishes between development, Space Lite, and full Space Level screening in its product documentation.

The new parts are aimed at a computing load that is becoming more demanding. FPGAs, SoCs, GPUs, and dedicated accelerators are increasingly used for onboard imaging, communications processing, autonomous functions, and AI inference. Those devices can require large, rapidly changing currents at low core voltages, creating the same basic point-of-load problem seen in terrestrial computing while adding radiation tolerance, launch vibration, vacuum thermal management, and long mission life.

Power density has system consequences in that environment. Energy lost in a converter becomes heat that cannot be removed by convection, while larger magnetics, heatsinks, and shielding add mass. Raising switching frequency can shrink some passive components, but only if the electrical and thermal design allows the GaN devices to operate fast enough to justify the change.

EPC Space cites voltage-regulator modules, intermediate voltage regulators, point-of-load converters, and intermediate bus converters as target applications, including power stages supporting devices such as Versal SoCs and Nvidia GPUs. Those examples describe the load class rather than tying the FETs to one processor vendor, and the same electrical requirements can appear around other high-current digital devices.

The launch therefore extends radiation-hardened GaN into a part of the power tree where low voltage and very high current coincide. The useful comparison will be made at converter level: efficiency across load, transient response, thermal behaviour, EMI, radiation qualification, and lifetime. Sub-milliohm resistance and fast switching provide the component-level starting point, but spacecraft designers still have to prove that the complete regulator can exploit those characteristics without creating a new thermal or reliability problem elsewhere.