A device includes an integrated circuit programmed with an operating surface equation. The operating surface equation may define an operating point as a function of operating voltage, operating frequency, and leakage current. The operating surface equation may be generated by fitting a surface equation to data for operating voltage and operating frequency versus leakage current for a plurality of test integrated circuits. An operating voltage of the integrated circuit at a given operating frequency may be determined by the operating surface equation and a leakage current value fused into the device.