A modular power supply. A plurality of power supply modules and a system control circuit for controlling the power supply modules are provided. Each power supply module has a power circuit coupled to a power input of the module for receiving an input power current and produces an output power current at a power output of the module. The power circuits each include at least one switching element for switching the input power current or the output power current of a module. The power circuits further include a control circuit input that is coupled directly to the respective said switching device. The system control circuit includes a control circuit output bus for connecting to the control circuit inputs of each of the power modules and provides a respective signal to each module for directly controlling the respective switching devices.