A switching converter produces an output signal transmitted to a variable load impedance to produce a load voltage V.sub.DD across the load impedance and holds V.sub.DD close to a set point voltage V.sub.SP selected by control data D.sub.REF1 to compensate for variations in the load impedance which tend to drive V.sub.DD away from V.sub.SP. The switching converter includes a pulse-width modulated power converter for producing the output signal of voltage V.sub.OUT in response to an input signal of voltage V.sub.IN, wherein a ratio V.sub.OUT/V.sub.IN is a function of a duty cycle D.sub.1 of a pulse-width modulated signal V.sub.PWM1. A pulse-width modulation circuit generates the V.sub.PWM signal of duty cycle D.sub.1 controlled by a control signal, and a feedback control circuit monitoring the load voltage V.sub.DD adjusts D.sub.1 to keep the load voltage as close as possible to V.sub.SP. A power source supplies the input signal of voltage V.sub.IN to the power converter. Second control data supplied to the power source separately selects the value of V.sub.IN for each possible set point voltage V.sub.SP such that that the pulse-width modulate signal's duty cycle D.sub.1 remains as close a possible to a value for which circuit performance is substantially optimal with respect to a selected combination of performance criteria.