A method is provided for optimizing power consumption of a digital circuit which provides operational functionality based upon operating demands. The digital circuit is subject to a supply voltage level and a clock frequency. The method includes determining an acceptable delay value, from a plurality of predetermined acceptable delay values, for the digital circuit based upon current operating demands and the clock frequency. The supply voltage level and the clock frequency are applied to a delay monitor circuit. The delay experienced by the delay monitoring circuit is measured. The measured delay is compared with the determined acceptable delay value. Based on the outcome of the comparing step, the supply voltage level applied to the digital circuit is selectively adjusted. An arrangement for implementing the method is also provided.