POWER BACKUP CIRCUIT OF MOBILE COMMUNICATION TERMINAL

PURPOSE: A power backup circuit of a mobile communication terminal is provided to bypass a switching element upon an emergency call after shutting off power supply to the mobile communication terminal according to voltage check result of a battery and to restart the power supply to the mobile communication terminal in order to provide the emergency call during a few minutes. CONSTITUTION: In a power backup circuit of a mobile communication terminal, an OP amplifier checks the voltage of a battery and transmits the voltage check result to an ADC in order to convert the voltage to a digital signal. A control part determines whether the data of voltage check result which are converted to the digital signal in the ADC are less than the predetermined voltage shutting down the battery or not. In the case of less than the predetermined voltage, the control part outputs a detection signal of the battery for working the forth transistor. The second transistor is turned off by working the forth transistor according to the detection signal of the control part and the third transistor is turned off by the second transistor turned off to shut off the power supply to the mobile communication terminal. In case that a user pushes an emergency key for the emergency call in the stat the power is shut off, the third transistor is turned on by working the fifth transistor according to input of an emergency key signal. Then, the control part output a restarting signal of power supply according to input of the emergency key signal. Thereafter, the second transistor is turned on and the fifth transistor is turned off by the restarting signal of power supply.