Apparatus and methods to regulate an input power applied to a plurality of light emitters are provided. A regulator device includes a plurality of switches and a control circuit that controls the plurality of switches. The plurality of switches selectively couple respective strings of the light emitters in series to the input power to emit light when deactivated. The control circuit may deactivate a number of the switches to couple the respective light emitters to the input power in response to a sensed operational parameter of the input power. The control circuit may adjust the number of the switches deactivated in response to a change in the sensed operational parameter of the input power. A number of the light emitters may be coupled to the input power regardless of the sensed operational parameter of the input power.