A power supply unit for an electronic device, in particular for a microprocessor, the power supply unit having an input section comprising input terminals connectable to a primary power source, the primary power source being configured to output a primary voltage, an output section comprising output terminals connectable to the electronic device and configured to output at least two secondary voltages (u1-u5) having different nominal voltage levels, and a power management section, the power management section being configured to perform a shutdown process upon existence of a shutdown criterion, wherein the shutdown process comprises decreasing each of the secondary voltages (u1-u5) down to a predetermined safety level in a controlled manner, wherein the power management section is configured to simultaneously decrease the secondary voltages (u1-u5) during the shutdown process, wherein the power management section is configured to simultaneously start with the decreasing of the secondary voltages (u1-u5) and to decrease the secondary voltages (u1-u5) during the shutdown process such that they simultaneously reach the safety level, wherein the power supply unit is a digital power supply unit having a plurality of DC-DC-converters respectively configured to provide the secondary voltages (u1-u5) and the power management section is configured to decrease the secondary voltages (u1-u5) during the shutdown process by reducing respective duty cycles of the DC-DC-converters, characterized in that the shutdown process comprises decreasing the secondary voltages (u1-u5) gradually applying individual decrements by means of a pre-programmed stepwise reduction of the duty-cycles of the DC-DC-converters. an input section comprising input terminals connectable to a primary power source, the primary power source being configured to output a primary voltage, an output section comprising output terminals connectable to the electronic device and configured to output at least two secondary voltages (u1-u5) having different nominal voltage levels, and a power management section, the power management section being configured to perform a shutdown process upon existence of a shutdown criterion, wherein the shutdown process comprises decreasing each of the secondary voltages (u1-u5) down to a predetermined safety level in a controlled manner, wherein the power management section is configured to simultaneously decrease the secondary voltages (u1-u5) during the shutdown process, wherein the power management section is configured to simultaneously start with the decreasing of the secondary voltages (u1-u5) and to decrease the secondary voltages (u1-u5) during the shutdown process such that they simultaneously reach the safety level, wherein the power supply unit is a digital power supply unit having a plurality of DC-DC-converters respectively configured to provide the secondary voltages (u1-u5) and the power management section is configured to decrease the secondary voltages (u1-u5) during the shutdown process by reducing respective duty cycles of the DC-DC-converters, characterized in that the shutdown process comprises decreasing the secondary voltages (u1-u5) gradually applying individual decrements by means of a pre-programmed stepwise reduction of the duty-cycles of the DC-DC-converters.