A 96.3-Efficiency Wide-Voltage-Range Three-Level Boost Converter With Loop-Free Self-Balancing and Dead-Zone PWM Control for Backlight LED Drivers

This article proposes a high-efficiency three-level boost converter that ensures reliable operation in wide input and output voltage ranges for light-emitting diode drivers. The proposed converter adopts robust auto calibration using half of the output voltage (V-OUT) for flying capacitor voltage (V-CF) self-balancing without requiring additional bulky feedback loops. In addition, the proposed dead-zone pulsewidth modulation control (DZPC) overcomes the limitations of irregular switching and output ripples near the duty 0.5 boundary by alternating between mode1 (D < 0.5) and mode2 (D > 0.5) at every cycle. The prototype converter was fabricated in a 180-nm Bipolar CMOS DMOS (BCD) process occupying a silicon area of 4.72 mm(2) while adopting a flying capacitor of 4.7 mu F and an inductor of 10 mu H. The peak efficiency was measured up to 96.3% at V-IN = 24 V, V-OUT = 30 V, and I-LOAD = 100 mA. The proposed loop-free self-balancing verified the reliable three-level conversion regardless of duty by maintaining V-CF at 0.5V(OUT), while DZPC also ensures efficient and seamless operation around the duty of 0.5.