High input voltage single-stage flyback AC/DC LED driver using series-connected MOSFETs

This paper deals with high input voltage LED driver with a requirement of power factor correction (PFC). A series-connected metal-oxide-semiconductor field-effect transistors (MOSFETs) circuit which can support high total blocking voltage is proposed. Compared with the existing series-connected devices methods, this circuit can efficiently and reliably operate in a wide voltage range situation. Thus it can be applied in low cost flyback-based single-stage PFC ac/dc converter. In this circuit, the main switch is directly driven by the control IC while the slave switch is driven by an auxiliary circuit. The auxiliary circuit can also realize effective voltage sharing. The turn-on and turn-off operation principle is analyzed in detail. Then voltage stresses of the devices are derived, and the power losses of the auxiliary circuit are calculated, meanwhile a method of decreasing the voltage stress and power losses is given. Design guidelines are also provided in this paper. Experimental results basic on a 75W prototype show the proposed circuit works well with a 480Vac input.