Synchronous rectifiers enable high efficiency for buck-boost converter

The online UPS is ideal for environments where electrical isolation is necessary or for equipment that is very sensitive to power fluctuations. As demand for longer battery life in online UPS increases, engineers are challenged to design highly efficient buck-boost converters. Adding to the challenge is the fact that many online UPSs have wide battery voltage variation. This paper discusses the replacing low effective Schottky-diode rectifiers with synchronous MOSFET rectifiers for the buck-boost converter. The discussion includes an example of buck-boost converter for Industrial Online UPS with 12V output, MOSFET selection, and an evaluation of in-circuit efficiency against the current commercial solutions based on Schottky-diode rectifiers.