Control device of an internal combustion engine, namely, for controlling injectors or gas valves of a fuel supply system of the internal combustion engine, wherein the control device controls each injector for opening the same such that the voltage present at the respective injector changes between different voltage levels in a boost phase of the control as well as in a hold phase of the control, and wherein the control device controls the respective injector in the boost phase such that after reaching a defined boost current level the voltage present at the respective injector changes between a relatively low boost voltage level which is greater than zero volts and a relatively high boost voltage level which is greater than a supply voltage of the control device.