Abstract: The present invention relates to a docking station that is operable as a host. The docking station is suitable for docking a portable device that is operable as a slave. The portable device may be, for example, a personal digital assistant (PDA) or a mobile phone. The docking station includes determination means for determining an operational voltage of the docked portable device. An adjustable power supply outputs a supply voltage to the docked portable device in accordance with the determined operational voltage. Typically, the power supply includes control means (e.g. microcontroller) for controlling the supply voltage outputted from the adjustable power supply. The present invention also relates to a method for outputting the supply voltage from the host docking station to the docked slave portable device.