Si Driver/GaN Power-Transistor Combo Promises Smaller, Faster Chargers and Power Supplies

Combining a silicon-based half-bridge driver and a pair of gallium arsenide (GaN) transistors, STMicroelectronics’ new MasterGaN family of devices is expected to form the foundation of next-generation compact and efficient chargers and power adapters for applications up to 400 W. That means smaller, ultra-fast smartphone chargers, wireless chargers, USB-PD adapters for PCs and gaming, and industrial applications such as solar-energy storage systems, uninterruptible power supplies, and OLED TVs.

Today’s GaN market is typically served by discrete power transistors and driver ICs, which designers must integrate for optimal performance. In what’s called a first, ST’s MasterGaN approach saves that time and effort while also assuring a high level of performance. Other benefits include a smaller footprint, simpler assembly, and higher reliability. Chargers and adapters based on MasterGaN can cut 80% of the size and 70% of the weight of all-silicon-based implementations.

The MasterGaN platform leverages STDRIVE 600-V gate drivers and GaN high-electron-mobility transistors (HEMTs). The 9-mm x 9-mm, 1-mm-profile GQFN package ensures high power density and is designed for high-voltage applications with over 2-mm creepage distance between high-voltage and low-voltage pads.

The family of devices will span different GaN-transistor sizes (R_DS(ON)) and will be offered as pin-compatible half-bridge products that let engineers scale successful designs with minimal hardware changes. Leveraging the low turn-on losses and absence of body-diode recovery that characterize GaN transistors, the products enhance the performance of high-end, high-efficiency topologies such as flyback or forward with active clamp, resonant, bridgeless totem-pole PFC (power factor corrector) and other soft- and hard-switching topologies used in AC/DC and DC/DC converters and DC/AC inverters.

The initial member of the device family is MasterGaN1, which is connected as a half bridge with integrated high-side and low-side drivers. The MasterGaN1 contains two normally-off transistors that feature closely matched timing parameters, 10-A maximum current rating, and 150-mΩ on-resistance (R_DS(ON)). The logic inputs are compatible with signals from 3.3 V to 15 V. Comprehensive protection features are also built in, including low-side and high-side UVLO protection, interlocking, a dedicated shutdown pin, and over-temperature protection.

MasterGaN1 is in production now and is priced at $7 in quantities of 1,000. An evaluation board is also available.

STMicroelectronics, www.st.com.