This paper presents a high-efficiency offline isolated LED driver based on a flyback converter. In order to achieve high power conversion efficiency as well as a low-cost design, a simple passive lossless turn-off snubber is proposed to reduce the switching loss of the power switch. A primary-side power regulation scheme is also proposed to compensate for forward voltage variation and aging caused by process and temperature variations. The proposed control scheme is designed and fabricated on-chip using a 0.35- $\mu\hbox{m}$ BCDMOS process. Test results of the proposed LED driver show an efficiency level that exceeds 83% (up to 90%) in an output range of 5–10 W with an input range of 85–265 ${\rm V}_{\rm AC}$.