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

摘要

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.