This paper proposes a novel single-stage ac-to-dc light-emitting-diode (LED) driver circuit. A buck-boost power factor (PF) corrector is integrated with a flyback converter. A recycling path is built to recover the inductive leakage energy. In this way, the presented circuit can provide not only high PF and low total harmonic distortion but also high conversion efficiency and low switching voltage spikes. Above 0.95 PF and 90% efficiency are obtained from an 8-W LED lamp driver prototype.Index Terms-AC-to-DC converter, energy recycling, light-emitting-diode (LED) driving circuit, power factor (PF) corrector (PFC).

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This paper proposes a single-stage electrolyticcapacitors-free ac-to-dc driving circuit for light-emitting-diode (LED). A buck-boost power factor corrector (PFC) is integrated with a flyback converter. In this way, the presented circuit can provide not only high power factor (HPF) and low total harmonic distortion (THD). The electrolytic capacitors can be replaced by multi-layer ceramic capacitors (MLCCs) via the conversion circuit integration. Above 0.97 power factor (PF) and 82% efficiency are obtained from a 5W LED bulb driver prototype.