A control device that controls a switching circuit and minimizes hard switching that occurs in the switching circuit of a half-bridge resonant converter having a high-side transistor and a low-side transistor. The control device is configured to turn the high-side and low-side transistor on and, so that a square-wave voltage is applied to a primary winding of a transformer. The controller starts the switching of the half-bridge converter by first turning on the low-side transistor for a first time period useful for pre-charging a bootstrap capacitor couplable to the middle point of the half-bridge, and then turning the low-side transistor and the high-side transistor off for a second time period that immediately follows and is longer than the first time period.