A power supply unit for an electronic device includes an input section comprising input terminals connectable to a primary power source, an output section comprising output terminals connectable to the electronic device and outputting at least two secondary voltages having different nominal voltage levels, and a power management section. The power management section is configured to perform a shutdown process upon existence of a shutdown criterion, wherein the emergency shutdown process comprises decreasing each of the secondary voltages down to a predetermined safety level in a controlled manner.