An apparatus comprises a linear power supply and an auxiliary power supply powered from the linear power supply. The auxiliary power supply comprises a switching regulator connected to receive, at an input thereof, the output voltage of the linear power supply and to generate therefrom an output voltage of the auxiliary power supply. The auxiliary power supply further comprises a detection circuit, connected to the linear power supply and to the switching regulator, that detects one of (i) a level of current drawn from the linear power supply and (ii) a level of voltage at an output of the linear power supply and that causes the switching regulator to reduce its load on the linear power supply when the detected level reaches a predetermined threshold.