An apparatus for supplying power in a mobile terminal is provided. The apparatus includes a battery, a power management integration circuit including a buck-boost converter for converting a battery voltage to output a specific voltage, and a plurality of regulators for regulating the specific voltage output from the buck-boost converter to voltages of respective corresponding constituent elements and for outputting the regulated voltages, the buck-boost converter operating in a buck mode when the battery voltage is greater than the specific voltage, and the buck-boost converter operating in a boost mode when the battery voltage is less than the specific voltage, such that the constituent elements include a controller for controlling an operation of the mobile terminal, a touch panel for generating an input and for providing the generated input signal to the controller, and a display unit for displaying an operation of the mobile terminal under control of the controller.