| 摘要 |
PURPOSE:To enable a user to speak for a long time by partially stopping the operation of a circuit where the supply voltage reaches a minimum guaranteed voltage and setting the other circuits to the operating state. CONSTITUTION:A microprocessor 4 always compares the signal from a power monitor circuit 3 with a prescribed value (V1>V2>V3). If the voltage of a secondary battery 1 falls and the signal from the power monitor circuit 3 is lower than V1, the microprocessor 4 commands a display device 8 to display an attention message, and the user is informed that the residual capacity of the secondary battery 1 is reduced. If the voltage of the secondary battery 1 is more reduced and the signal is lower than V2, the microprocessor 4 inhibits write to a memory 5 and commands a sound processing circuit 6 to generate an alarm tone and commands the display device 8 to display an alarm message, thus giving an alarm to the user. If the voltage of the secondary battery is reduced furthermore and the signal is lower than V3, the microprocessor 4 commands a power source circuit 2 to turn off the power source and stops all of the operation of a portable telephone. |
