| 摘要 |
<p>PURPOSE:To make the device highly reliable and reduce the cost by performing switching control over a battery without any momentary break by detecting a potential difference generated across a resistance with a discharging current. CONSTITUTION:In a normal power supply state, a charging current flows in a capacitor 7, and its voltage drop causes the output of a comparator 5 to go down to a level L. When the battery back 1a for power supply is extracted, the capacitor 7 supplies the discharging current to a DC-DC comparator 8 through a resistance 6. At this time, the output of the comparator 5 rises to a level H. A microprocessor 3 detects the variation in the output of the comparator 5 to recognizes the extraction of the battery pack 1a and turns on a discharge switch 2b which is OFF so far, thereby allowing the power supply from the battery pack 1b. Consequently, the switching control over the battery is performed without any momentary break and the device is made high in reliability and reduced in cost.</p> |
