Design and analysis of 37.5% energy-recycling flyback-type class-D gate driver IC with 5-to-15V level-conversion

This paper presents an energy-recycling class-D gate driver IC which can also perform 5-to-15V level up-conversion using a bidirectional flyback converter topology. The gate driver itself is a mini switching regulator that operates at 5~15-MHz to generate 1-μs transition time gate-switching waveforms. In order to maintain uniform charging/discharging currents during transitions, the embedded flyback converter operates in a pulse-frequency modulation (PFM) mode while charging and in a pulse-width modulation (PWM) mode while discharging the gate node. The required pulses with digitally programmable frequencies and duty-cycles are efficiently generated by a custom-designed IC, fabricated in a 0.25-um HV CMOS technology. Also, the presented analysis guides a way to achieve the desired transition time with the maximum efficiency. The prototype IC demonstrates 37.5% energy recycling while driving a 15-V IGBT power switch with 105-nC gate charge at 20-kHz.