| 摘要 |
PROBLEM TO BE SOLVED: To store a data memorized in a memory by outputting a predetermined operating voltage constantly to a memory IC until the voltage from a discharge circuit is reduced to a predetermined minimum data retaining voltage level. SOLUTION: A terminal of a battery B is grounded through a second resistor R2 and a transistor Q upon power interruption. First and second resistors R1, R2 divide n input applying voltage 5V and charges the battery B to sustain a voltage of 3.0V. A first diode D1 applies the voltage of battery B only to the DC-DC converter section 30 in power interruption. Data memorized in the memory is stored for a long time by feeding an output voltage of 5V to a microcomputer IC 13 until the voltage being fed from the battery B in power interruption in the backup mode, i.e., low power consumption mode, of DC-DC converter section 30 drops below the minimum data retaining voltage, i.e., 1.5V. |
