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
μ
F and an inductor of 10
μ
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 0.5
V_OUT
, while DZPC also ensures efficient and seamless operation around the duty of 0.5.