A power supply includes circuitry for gradually enabling switching rectifiers during a startup condition without drawing current from a pre-biased power supply output. A driver provides a control signal to synchronous rectifier. A driver supply circuit is coupled across the driver and has a first input receiving pulse signals provided by a pulse modulation controller, an output providing supply voltage to the driver, a second input receiving driver supply input voltage, and circuitry defining a time constant. The circuitry includes a first switching element that turns on when pulse signals are provided and a second switching element connected to the output. The time constant is associated with a rise time for the power supply, and defined by selected component values, such that the second switching element only becomes fully conductive after elapsing of the time constant.