GaN flyback converters target compact 100W power designs

Power conversion in compact electronics increasingly requires higher efficiency and reduced component count, particularly in appliances and consumer devices operating across wide input ranges. In this context, STMicroelectronics introduced two monolithic GaN-based flyback converters designed for 100W power supplies across consumer, industrial, and building automation applications.

Integrating GaN switching into compact power stages
The VIPerGaN100W and VIPerGaN100WB devices combine a 700V gallium-nitride power transistor, gate driver, and flyback controller within a single 5 mm × 6 mm QFN package. This level of integration reduces the need for external tuning of gate resistance and inductance, simplifying circuit design while maintaining switching performance.

The converters support universal AC input from 85 V to 265 V and deliver 100 W at 185 V input. The VIPerGaN100W provides a 3.5 A drain current limit, while the VIPerGaN100WB increases this to 4.2 A, enabling short-duration peak power up to 125 W. This headroom is relevant for loads such as motors and solenoids found in appliances including air conditioners and coffee machines, where transient demand can exceed nominal ratings.

Switching behavior tuned for efficiency and stability
Both devices operate as quasi-resonant flyback converters with zero-voltage switching, reducing switching losses and improving efficiency. Power management features adjust switching frequency across load conditions, including frequency foldback at light load and valley-skipping at intermediate load levels.

A proprietary valley-lock mechanism stabilizes the number of skipped valleys, preventing low-frequency oscillations that can produce audible noise. At no load, burst-mode operation reduces input power consumption below 30 mW, aligning with energy efficiency requirements for standby operation in consumer electronics.

Line-voltage feedforward maintains consistent energy transfer per cycle despite input voltage variation, while dynamic blanking time limits switching frequency shifts to reduce losses.

Power density gains enabled by high-frequency operation
The use of GaN transistors enables higher switching frequencies compared to silicon-based designs, allowing smaller passive components and increasing power density. This is reflected in the EVLVIPGAN100WP reference design for a 100W USB Type-C Power Delivery 3.0 adapter based on the VIPerGaN100W.

The reference design supports output profiles from 5 V/3.0 A to 20 V/5.0 A with secondary-side regulation and optocoupler feedback. Reported performance includes peak efficiency above 92 percent and a power density of 24 W/in³, indicating suitability for compact chargers and embedded power supplies.

Electrical robustness and protection features
Each converter integrates protection mechanisms for input and output overvoltage, overtemperature, and brown-in and brown-out conditions. The GaN transistor exhibits an RDS(on) of 0.27 mΩ, contributing to reduced conduction losses and improved thermal behavior under load.

These characteristics position the devices for use in applications such as smart lighting, home automation systems, televisions, and chargers, where efficiency, size constraints, and reliability are critical within a broader digital supply chain of connected electronic products.

Edited by Aishwarya Mambet, Induportals Editor, with AI assistance.

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