High-accuracy passive current balancing schemes for large-scale LED backlight system

In this paper, two high-accuracy low-cost current balancing circuits are proposed for LED backlight system by using capacitors and mini transformers. Compared with traditional active and passive balancing approaches, the proposed schemes greatly reduce cost and power losses, and achieve highly accurate current matching among all LED strings in wide dimming ranges. The current balancing principles of the proposed circuits are analyzed, and high accuracy designs are verified by simulation and experimental results.