Design and Analysis of 37.5% Energy-Recycling Flyback-Type Class-D Low-Side Gate Driver IC with 5-to-15-V Level Conversion

This paper presents an energy-recycling class-D low-side gate driver integrated circuit (IC), which can also perform 5-to-15-V level upconversion 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 mode while charging and in a pulse width modulation 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-μm 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 insulated-gate bipolar transistor power switch with 105-nC gate charge at 20 kHz.