STMicroelectronics VIPerGaN 100 W converters for energy-efficient appliances

STMicroelectronics’ two 100-watt VIPerGaN high-voltage converters are designed to extend wide-bandgap energy savings throughout domestic appliances, building and home automation, smart lighting, and consumer products including televisions and device chargers.

The VIPerGaN100W has a 3.5 A drain current limit, while the VIPerGaN100WB has a 4.2 A current limit for handling short-term peak power up to 125 W. The extra flexibility saves designers over-specifying power circuitry in equipment containing inductive loads like solenoid valves or motors, such as in coffee-makers, small appliances and air-conditioners. Both converters are compatible with the universal AC input voltage range, from 85–265 V, and will deliver 100 W from 185 V supply.

The 700 V gallium-nitride (GaN) power transistor in each converter is intended to provide ruggedness and reliability, with low R_DS(ON) of 0.27mΩ that helps achieve good thermal performance. The 5 x 6 mm QFN devices also integrate the flyback converter as well as the GaN gate driver, which saves designers fine-tuning gate resistance and inductance to optimise switching performance. On the other hand, leveraging the high switching frequency possible with GaN power transistors lets circuit designers use small passive components to achieve good energy efficiency and power density.

The VIPerGaN100W and VIPerGaN100WB each contain a flyback converter that operates in quasi-resonant mode with zero-voltage switching. Here, flexible power management limits the switching frequency to support optimal efficiency across the load range, including frequency foldback at light load and valley skipping at mid load.

Line-voltage feed-forward sharpens control of energy per cycle, stabilising power as the input voltage fluctuates. Also, dynamic blanking time limits the change in switching frequency to minimise switching losses. Both converters integrate protection against input and output overvoltage, overtemperature, brown-in and brown-out.