A method of operating an electronic circuit including: a master converter including a master controller and a switch, a slave converter including a slave controller and a switch, designed to step up an input voltage of the electronic circuit to an output voltage, each converter operating in a quasi-resonant mode by zero-voltage switching of their respective switch, wherein: the master controller sends, when the master converter switch is turned on and when a preset phase-shift criterion is met, a control signal to the slave controller which turns off the slave converter switch, the master and slave controllers turn on the switch of their respective converter as soon as a zero voltage is detected across the terminals of the switch, wherein the electric current magnitude in the master converter switch is measured, and the preset phase-shift criterion is met when the measured magnitude reaches a preset value.