Transphorm’s high-voltage GaN FETs amp up Marotta Controls’ military-grade high-frequency power supply

Transphorm Inc of Goleta, near Santa Barbara, CA, USA — which designs and manufactures JEDEC- and AEC-Q101-qualified high-voltage (HV) gallium nitride (GaN) field-effect transistors (FETs) for high-voltage power conversion applications — says that aerospace & defense supplier Marotta Controls’ upcoming power supply unit (PSU) replaces incumbent silicon (Si) MOSFETs with high-voltage GaN PQFN devices.

Marotta’s latest design operates at high frequency in a conduction-cooled mechanically constrained envelope. The supply’s topology features hard switching and an automatic transformer RESET capability where transistor voltage stresses are clamped to the input voltage. The GaN devices increase the PSU’s efficiency dramatically and alleviate a complex thermal design in the small-form-factor package.

“The demand on our power supplies and expectation of performance is high,” says Marotta Controls’ principal engineer Mike Scruggs. “This particular complex PSU needed to reliably convert and distribute power in a small envelope. The system design had to work considerably higher than 100kHz to reduce the power component’s size, but our engineering team met challenges with heat dissipation and component temperatures under peak load conditions,” he adds. “In our search beyond standard transistor solutions we were led to find Transphorm’s high-voltage GaN technology.”

After testing Si-based prototypes, Marotta vetted Transphorm’s TPH3208LD PQFN package, which reached the desired switching speeds with significantly reduced losses. The GaN devices’ dissipation significantly decreased compared with that of the Si MOSFETs’, resulting in lower board component temperatures. This, in turn, yielded a simpler viable thermal design and packaging concept for the overall system.

“We initially selected Transphorm’s transistors for the reputable reliability, and our experience has since exceeded our expectations,” comments Steve Fox, Marotta Controls’ VP of engineering and program management & chief technology officer. “Transphorm’s GaN enabled us to not only gain high power efficiency and thermal performance but also generated power savings in the drive and control circuitry — additional benefits that will provide opportunities in future designs. Transphorm’s ability to align with our vision of providing advanced, next-generation technologies — combined with their exceptional level of technical support and dependability — are the exact characteristics we look for in our growing supplier base,” he adds.

“Marotta’s design success is important for several reasons,” says Philip Zuk, Transphorm’s VP of worldwide technical marketing. “First, it indicates yet another hard-switched topology type that can effectively leverage high-voltage GaN. Second, Marotta completed its design with minimal assistance from Transphorm’s application support team — indicating that the market’s initial concern that design challenges would slow GaN adoption can be addressed through the use of Transphorm’s GaN FETs.”

The release of Marotta’s high-frequency PSU is scheduled for January. The product will mark the aerospace & defense industry’s first publicly recognized high-voltage GaN-based power supply, it is reckoned.

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Tags: Transphorm GaN-on-Si GaN HEMT Power electronics

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