High power factor LED power supply based on SEPIC converter

A single-ended primary inductor converter (SEPIC)-based light-emitting diode (LED) power supply, which can achieve power factor correction (PFC) and constant-current drive for LED in the critical conduction mode (CRM), is presented. The circuit principle is described in detail. Meanwhile the formulas for metal-oxide semiconductor field-effect transistor switch-on time, switching frequency and the main influences of power factor are given. Experimental results show that the power can drive the LED with high efficiency by virtue of its high power factor, low power loss and stable output. Furthermore, it can be applied to low-power lighting occasions with simple structure and high reliability.