STEVAL-250GANCB

STEVAL-250GANCB is an AC/DC power adapter consisting of three stages: a totem pole PFC (AC/DC) working in zero voltage switching, variable frequency mode; a resonant half bridge LLC converter (DC-DC), and a synchronous rectification output stage.

High-power density is achieved thanks to the GaN switches SGT120R65AL, combined with STGAP2GS GaN driver.

The SGT120R65AL will be soon replaced by the new SGT100R70FDC.

The solution uses a single microcontroller STM32G474RE to control the PFC and primary side of LLC. The synchronous rectification stage is controlled by the SRK2001 and two parallel STL120N10F8 STripFET F8 power MOSFETs.

The totem pole PFC operates in ZVS with variable switching in the range of 35 ÷ 300 kHz, from light load to full load.

The LLC implements frequency modulation to regulate the output voltage and operates at variable frequency from 200 to 300 kHz, with a resonance frequency of 227 kHz. The startup phase is performed at high frequency from 500 down to 200 kHz.

Thanks to the excellent switching performance of GaN devices at high frequency and the soft switching techniques (ZCS and ZVS) in all stages, a peak efficiency of 96% was achieved.