| 摘要 |
PURPOSE:To reduce the power consumption of a backup power supply by connecting a transistor in series to a voltage detecting resistance and a control electrode of the transistor to an input power supply terminal respectively. CONSTITUTION:When the voltage impressed to an input terminal 1 is lowered, the gate voltage of an n channel MOSFET9 is also lowered and then cut off. Then an output terminal 2 has a high impedance. Thus a battery used as a power supply has no reduction of its lifetime in case a packup power supply is connected to an output terminal 2. Thus it is possible to secure the desired holding time even with a battery of a small capacity. |
