An apparatus for controlling power consumption in a Personal Digital Assistant (PDA) phone is provided. The apparatus includes a PDA controller for applying a first signal or a second signal to a PDA voltage module, for sensing a voltage of a first capacitor changed according to the first or second signal, and for operating at the voltage of the first capacitor, and the PDA voltage module in which a first resistor is in a shorted or open condition according to the first or second signal, and a voltage applied to the first capacitor is changed according to the shorted or open condition of the first resistor.