Over at least part of a lifetime of a product circuit, quiescent current to a product circuit is periodically measured. Over the part of the lifetime of the product circuit, voltage to the product circuit is periodically adjusted based on the monitored quiescent current. Methods, apparatus, and computer program product are disclosed. A calibration procedure may also be performed as part of manufacturing the product circuit, in order to provide values for the quiescent current and corresponding voltage to which the voltage should be adjusted.