Smart Diode and 4-Switch Buck-Boost Provide Ultra High Efficiency, Compact Solution for 12-V Automotive Battery Rail

DC-dc converters operating off the 12-V auto rail have to deal with reverse battery condition as well as wide input voltage range. The traditional solutions include PFETs for reverse battery and a buck-boost solution utilizing two stages or multiple windings. Both of these result in higher losses and bulky solution size. This paper presents and approach consisting of smart diode and 4-switch single-inductor buck-boost converter. The smart diode provides an efficient diode or PFET replacement while the single inductor buck-boost provides ultra-high efficiency buck-boost conversion stage in a small solution size.