1. A digital device having operating parameters associated with and optimized for each one of a plurality of different clock frequency ranges, comprising: a digital function having a set of operating parameters optimized for each one of a plurality of different clock frequency ranges; logic circuits having a set of operating parameters optimized for each one of the plurality of different clock frequency ranges; a configuration register for programmabley selecting one of the plurality of different clock frequency ranges; wherein the sets of operating parameters associated with the selected one of the plurality of different clock frequency ranges are applied to operation of the digital function and the logic circuits; and a clock source selection bits in the configuration register, wherein the clock source selection bits determine selection of a clock source for operation of the logic circuits and digital function; wherein the logic circuits are coupled to an external clock selected by the clock source selection bits in the configuration register.