US Patent 10212770 AC-DC single-inductor multiple-output LED drivers

A single-stage AC-DC single-inductor multiple-output (SIMO) LED driver uses a single inductor (L) to drive multiple independent LED strings (341-34n) with Power Factor Correction (PFC). The driver uses a diode bridge (20) to achieve initial AC to DC conversion. The output of the bridge (20) is provided to a buck converter whose output is shared with multiple LED strings by a time division multiplex circuit. Feedback is used to separately control the current supplied to each LED string by using a separate reference for each string and controlling the width of the current pulse provided to a string. Current balancing in every LED string can be achieved with the same voltage reference without the need for additional circuitry.