A drive system for multiple LED strings powered by a common line voltage. Current control circuits are connected in series with respective LED strings; each current control circuit includes a drive transistor (typically a FET) which causes a desired LED string current to be conducted. In one embodiment, the current conducted by a selected one of the LED strings is controlled by the line voltage regulation loop, while the currents conducted by the remaining LED strings are controlled by respective local current loops, thus avoiding conflicts between the local current and line voltage regulation loops. The LED string to be current regulated by the line voltage regulation loop can be determined by a variety of criteria, such as the current control circuit having the maximum FET gate voltage, the minimum FET source voltage, the minimum FET drain voltage, the maximum FET gate-source voltage, or the minimum FET drain-source voltage.