ST simplifies high-efficiency two-port USB-PD adapters

02 February 2023

STMicroelectronics has extended its highly integrated and power-saving ST-ONE family of USB-PD digital controllers with the ST-ONEMP, which supports two power outputs.

The ST-ONEMP builds on the market-first ST-ONE architecture combining an Arm Cortex-M0+ microcontroller, energy-efficient non-complementary active clamp flyback controller, and USB-PD 3.1 interface in a single package. Using galvanic isolation between primary-side and secondary-side circuitry, the ST-ONE architecture greatly simplifies the design and assembly of USB-PD power adapters.

Now, by adding support for power sharing, the latest ST-ONEMP simplifies implementing a second output in addition to the USB-PD output to enhance flexibility and convenience for end users.

Inside the ST-ONEMP, the Cortex-M0+ MCU is embedded on the secondary side and has 64KB of Flash for customizing the USB-PD protocol and power conversion firmware. USB-PD 3.1 PPS certified firmware is pre-loaded, permitting a turnkey solution for standard applications. The MCU controls the synchronous rectifier and the flyback converter and is optimized for zero-voltage switching non-complementary active-clamp topology, which allows high power with greater efficiency than conventional quasi-resonant flyback.

The ST-ONEMP pairs with ST’s MasterGaN power technology, which contain ST’s gallium nitride (GaN) wide-bandgap power transistors with integrated gate drivers. ST’s GaN technology permits superior switching at higher frequencies than conventional silicon MOSFETs, enabling adapters to deliver greater power density with high energy efficiency meeting the latest ecodesign codes.

ST has produced the EVLONEMP reference design leveraging ST-ONEMP and MASTERGAN4 to create a 65W + 10W AC/DC adapter at comparable weight and volume to a 20W single-port smartphone charger. Peak efficiency, at 94%, is 2% higher than comparable conventional 2-port adapters, while the PCB area is a quarter of the size. OEMs can thus deliver more environmentally friendly products that save energy and cut the use of plastics by enabling smaller enclosure sizes.

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