Patent ID: 7375476

Claim:
A lighting device comprising a circuit, the circuit comprising: a power supply that provides a supply voltage; a plurality of light emitting diodes connected in series with said power supply and powered by the supply voltage, said plurality of light emitting diodes including at least two groups of series-connected light emitting diodes, said groups of series-connected light emitting diodes being connected in series; a plurality of optically isolated field effect transistors, a different optically isolated field effect transistor being connected in parallel with each group of series-connected light emitting diodes, for selectively shunting around the group of series-connected light emitting diodes to which the optically isolated field effect transistor is connected in parallel; and a controller connected to a gate of each of said optically isolated field effect transistors for selectively turning said optically isolated field effect transistors on and off, whereby said controller is electrically isolated from the supply voltage by said optically isolated field effect transistors.