A device for regulating a light source of a position-measuring unit includes: a measuring standard device that is movable relative to the light source; and a plurality of photodetectors, the photocurrent of at least one of the photodetectors usable as a basis for forming an actual value. The photodetectors are arranged such that light modulated by at least a partial number of the photodetectors of the measuring standard device is convertible into position-dependent photocurrents. In addition, the position-measuring unit includes a device for generating a setpoint value, and a comparator, by which a comparison between the actual value and the setpoint value may be made. By the generation device, the setpoint value is able to be generated based on the position-dependent photocurrents. A method is for performing such a regulation.