STMicroelectronics’ chip boosts energy efficiency in consumer electronics

The innovative chip, called ST-ONE, sets to increase energy efficiency in a wide variety of ac-dc adapters. It is fully compliant with USB-PD 3.1, including laptop and smartphone chargers. Adapters built with ST-ONE can reduce CO2 emissions and the quantity of plastics consumed.

The chip pairs with ST’s MasterGaN power output modules based on advanced gallium-nitride (GaN) semiconductor technology. The GaN chips enable significant energy savings and smaller equipment dimensions.

Although laptops provide optional power-saving settings, every machine can save even more energy if equipped with a more efficient power adapter. This improves the environmental profile and CO2 footprint. The ST-ONE chip is optimised for controlling power supplies that recover energy normally dissipated as heat from conventional circuits. It also simplifies circuit design with a significant reduction in the number of components, enabling this type of power supply to become more robust, affordable and widely adopted throughout the market.

“If every power adapter achieved at least 1% higher efficiency, which is possible using the ST-ONE energy-recovery circuit design, the world could save about 93TW hours of energy, equivalent to the output of 15 nuclear plants,” commented Domenico Arrigo, Industrial and Power Conversion Division General Manager, STMicroelectronics. “In addition, if one billion chargers worldwide were to use our technology, 0.2 million tons of plastics and raw materials could be saved.”

The reduction in consumption of materials such as plastics is achieved with the increase in so-called power density that enables smaller components to manage a larger power delivery. A high-power density also cuts down recycling and environmental costs.

On display at the Embedded World exhibition, ST’s reference design, EVLONE65W, enables a 65W USB-C adapter of the same size and weight (less than 70g in a 37cm3) of a standard 20W smartphone charger to handle the demands of charging a laptop. This unit achieves the world’s highest power density, packing more than 1.8W of power per cubic centimeter.

Further technical information

ST-ONE is optimised for designs based on a novel non-complementary active-clamp flyback topology, which allows high power, above 65W, with higher efficiency than other topologies such as the quasi-resonant flyback.

The digital controller integrates a programmable offline power-supply controller based on Arm Cortex-M0+ core, a high voltage start-up circuit, a synchronous-rectification controller, and USB Power Delivery (USB-PD) circuitry in one package.

The ST-ONE contains the required peripherals to control the conversion. USB-PD communication is implemented on the secondary side and reinforced galvanic isolation is provided to let the primary and the secondary side circuits communicate while respecting safety requirements.

Using the MasterGaN integrated power stage with advanced wide-bandgap transistors and optimised drivers, adapters operate at elevated switching frequencies and permit smaller-size magnetic components to maximize power density.

The ST-ONE comes with 64kByte of embedded flash for designers to customise both the USB-PD protocol and the power-conversion stage.

The ST-ONE controller comes with USB-PD 3.1 PPS certified firmware pre-loaded into the flash memory, presenting users with a turnkey solution for designing standard applications.