Embodiments of the present invention relate to methods and circuits for use with a system including a light emitting element (e.g., a laser diode or light emitting diode) that is driven by a current produced by a current output digital-to-analog converter (DAC), wherein the light emitting element or the DAC is powered by a supply voltage produced by a voltage supply. In accordance with an embodiment, a measure indicative of a voltage at an output of the DAC is obtained, wherein the voltage at the output of the DAC is indicative of a voltage headroom available for the DAC. The measure indicative of the voltage at the output of the DAC is compared to one or more predetermined references, and the supply voltage is controlled based on the comparison(s).