8.7 A 2MHz 4-to-60VIN Buck-Boost Converter for Automotive Use Achieving 95% Efficiency and CISPR 25 Class 5 Standard

Abstract

High-voltage highly efficient switching power converters have gained high popularity in automotive applications. Powered by the car battery $(V_{IN})$, the converters need to experience a wide $V_{IN}$ range from 4V to 60V under harsh cold crank and load dump environments. This requires the converter to accomplish a fine output voltage $( V_{OUT})$ regulation, seamless mode transition for $V_{IN}$ above, below or equal to $V_{OUT}$. Conventional buck or boost converters can only achieve monotonic step-down or step-up conversion. Other solutions such as standalone boost and buck, or SEPIC converters [1, 2] either require multiple cascaded power stages or suffer from lower system efficiency, larger footprint and higher bill-of material cost. The buck-boost converter thusly becomes a promising topology by its rather simple power-stage structure and wide conversion ratio [3–5]. However, the electromagnetic interference (EMI), power loss, and complicated control scheme are challenging with its inherent four-switch operation.