Rompower Energy Systems Inc. today announced best in class efficiency results for its 140W AC-DC adapter design, outperforming leading competitive solutions across the universal input voltage range. The superior performance is enabled by Rompower’s proprietary Ideal Flyback topology, which delivers high efficiency, high power density, high reliability and low cost using a single power switch and overall lower parts count.

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Rompower 140W Efficiency vs Line Graph

The Ideal Flyback is a simple single-switch flyback topology with a novel passive clamp that incorporates three proprietary technologies, enabling it to rank among the most competitive power-conversion solutions. The design is in compliance with the USB Power Delivery (PD) 3.0 and (PD) 3.1, while preserving its defining attributes of simplicity and low cost, unlike conventional high-performance power architectures that rely on complex multi-switch designs.

The first novel technology is a passive leakage-energy harvesting technique that eliminates the need for an active clamp. In this approach, the energy stored in the transformer’s leakage inductance is recovered passively and reused to support zero-voltage switching (ZVS) of the primary switch. This method not only suppresses voltage stress and ringing but also recovers energy that would otherwise be dissipated, thereby improving efficiency.

The second novel technology is a current-injection circuit that uses the energy harvested from transformer’s leakage inductance to generate a narrow, quasi-resonant current pulse in the transformer primary winding. This injected current discharges the parasitic capacitances reflected across the primary switch, ensuring ZVS under all operating conditions, including light-load and burst-mode operation.

Unlike conventional approaches where the energy stored in parasitic capacitances is dissipated during hard switching, this technique recovers that energy and returns it to the input voltage source, making it the most efficient known method for achieving ZVS in a single-switch flyback converter. As a direct consequence of guaranteed ZVS, no voltage spikes are generated across the synchronous rectifier, eliminating the need for secondary-side snubbers and further reducing losses and component count.

The third novel technology is a unique magnetic structure designed to inherently suppress common-mode noise within the transformer itself. By significantly reducing common-mode emissions at the source, the required EMI filter size is dramatically reduced, leading directly to higher power density and improved system efficiency.

“We continuously strive to lead the evolution of power-conversion technology,” said Ionel “Dan” Jitaru, Ph.D., Founder and CEO of Rompower Energy Systems Inc. “Our efforts are centered on developing breakthrough solutions in advanced power architectures.”

We greatly appreciate the support of Weltrend for providing technical guidance on the USB Power Delivery controller, WT6676F.

About Rompower Energy Systems Inc.

Rompower is an internationally recognized research and development company specializing in advanced power-conversion technologies. The company focuses on delivering innovative solutions for the power-electronics industry, including high-efficiency AC-DC and DC-DC converters, advanced magnetic designs, and next-generation power architectures for modern automotive and artificial-intelligence applications.

For more details, please visit our website at http://www.rompower.com.

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