A compact power platform combines GaN switching and digital control to improve USB-C charging efficiency, light-load performance, and system cost.
The 140W USB-C Power Delivery AC/DC reference design provides engineers with a platform for developing high-performance notebook adapters and other USB-C-powered equipment. Developed by Eggtronic using Renesas high-voltage GaN technology, the design targets a conversion efficiency approaching 96% while maintaining a bill of materials comparable to that of conventional quasi-resonant (QR) flyback solutions. The reference platform combines Eggtronic’s EPIC combo controller with Renesas’ TP70H150G4LSG, a 700V GaN transistor with 150 mΩ RDS(on), to create a compact power-conversion architecture suited to high-power USB-C applications.
The design is intended to address the efficiency, thermal, size, and cost challenges associated with conventional high-power USB-C adapters. Rather than using more complex and potentially costlier LLC, asymmetrical half-bridge (AHB), or active-clamp flyback (ACF) architectures, the platform employs Eggtronic’s proprietary QuarEgg regenerative flyback topology. This architecture uses a single primary-side switch and is designed to provide higher conversion efficiency while retaining the relatively simple implementation and component economics associated with QR flyback converters. For engineers developing compact adapters, the approach can help reduce power-stage complexity while supporting higher output-power requirements.
The EPIC combo controller provides a high level of functional integration within the reference design. Its functions include totem-pole power factor correction (PFC), isolated primary-side regulation, synchronous rectification, isolated communication, and USB Power Delivery protocol management. Integrating these functions into one controller can simplify the overall system architecture and reduce the number of discrete control components required in the design. The controller also incorporates Eggtronic’s proprietary ultra-low-latency isolated communication technology for coordinating functions across the isolation barrier.
The input stage uses a totem-pole PFC implementation designed to maintain high efficiency while addressing common design challenges involving electromagnetic interference (EMI) and reduced efficiency under light-load conditions. The PFC stage supplies the subsequent QuarEgg regenerative flyback converter, creating a two-stage AC/DC power architecture for the 140W USB-C PD output. The combination of high-voltage GaN switching and digital control is particularly relevant to engineers seeking to increase switching performance without moving to significantly more complicated power topologies.
Performance is maintained across a broad operating range. The reference design is specified to reach 94.5% efficiency at a 90VAC input, while peak efficiency approaches 96%. Its light-load performance is also intended to support compliance with stringent energy-efficiency requirements, including DOE Level VII. This makes the platform relevant to always-connected adapters where standby and low-power operation can contribute significantly to overall energy consumption.
For product developers, the board serves as a starting point for premium laptop chargers, notebook adapters, and other high-power USB-C PD equipment. By combining the TP70H150G4LSG GaN transistor with integrated digital power-management functions, the reference design offers engineers a path toward high-efficiency USB-C power supplies without the component count and architectural complexity typically associated with higher-power converter topologies.
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