Introduction

This application note describes the characteristics and features of a 150 W SMPS demonstration board (EVL150W-ADP-SR), tailored to all-in-one computer power supply (PS) specifications.

The characteristics of this design are the very high efficiency and low consumption at light load which make it a viable solution for applications compliant with ENERGY STAR® eligibility criteria (EPA rev. 5.0 computer and EPA rev. 2.0 EPS). One of the key factors to achieving high efficiency at heavy load is the SRK2000. This synchronous rectification (SR) driver for LLC resonant converters allows a significant decrease in secondary side losses.

Standby consumption is very low thanks to the sleep function embedded in the SRK2000 and the high voltage start-up circuit integrated in the L6563H. The possibility of driving the PFC burst mode via the L6599A PFC_STOP pin dramatically boosts light load efficiency.

Additionally, a secondary sensing circuit, dedicated to driving the primary controller into burst mode, reduces deviation of light load efficiency against resonant circuit parameter spread, improving the repeatability of design in production volumes.