Industrial Electronics

New reference design for USB Type-C power adapters

16 February 2021

A new USB Type-C power delivery 3.0 reference design with programmable power supply (PPS) support from ST Microelectronics is engineered to accelerate the design of easy-to-use, compact and efficient power adapters up to 27 W with zero-power operation when no cable is connected. USB PPS helps to save power, reduce device-charging times and heat dissipation, and lower bill-of-materials costs on the device side.

The STEVAL-USBPD27S reference design combines the STM32G071 microcontroller (MCU), which integrates a complete USB Type-C power delivery controller on-chip, with the STCH03 state-of-the-art pulse width modulation controller (PWM) and TCPP01-M12 USB Type-C protection integrated circuit. With this reference design, users can quickly build fast-charging USB power adapters that meet the stringent Source: ST MicroelectronicsSource: ST MicroelectronicsEuropean CoC version 5 Tier-2 and U.S. Department of Energy Level VI requirements for minimum four-point average efficiency in active mode and standby power below 40 mW.

The STM32G071 MCU handles the entire digital control section, including the algorithm to control VBUS on the secondary side as well as ST’s unique and patented algorithm for adaptive synchronous rectification, which enhances energy efficiency. The VBUS-control algorithm meets the USB Type-C power delivery and PPS specifications and implements cable-drop compensation for precise control of the supplied voltage. PPS support enables the output voltage to be adjusted in 20 mV steps between 3.3 V and 11 V, as well as current limiting adjustment in 50 mA increments, to minimize conversion losses during charging.

As an MCU-based solution, the reference design gives users extra flexibility to implement additional customized application layers and to incorporate ongoing improvements as the USB power delivery standard evolves.

The power section of the STEVAL-USBPD27S leverages ST’s highly integrated STCH03 PWM controller, which features built-in high-voltage start-up circuitry, primary-side constant-current output regulation, and advanced power management. Designed for quasi-resonant zero-voltage switching (ZVS) flyback converters, the STCH03 ensures high efficiency, ultra-low standby consumption and excellent dynamic performance.

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