BATTERY-DRIVEN ELECTRONIC DEVICE AND MOBILE COMMUNICATION APPARATUS

The present invention provides a battery-driven electronic device for which a long time use of the battery can be achieved and mobile communications equipment such as a portable telephone. Even if the time at which the output voltage of a battery 201 becomes below the supply voltage required by a load 206 including a power amplifier for wireless communications comes earlier than a conventional lithium ion battery because of its discharge characteristics that the battery voltage change ratio is 0.25 or more, a step-up and -down converter 200 operates as follows. When the output voltage of the battery is higher than the supply voltage required by the load, the voltage is set to a predetermined supply voltage by the step-down operation mode. When the output voltage of the battery is decreased and becomes lower than the supply voltage required by the load, the voltage is set to a predetermined supply voltage by the step-up operation mode. Thus, even for a battery employing a new material having a high energy density, a long term use of the battery can be achieved.