| 摘要 |
PURPOSE:To reduce not only the overdischarge of an internal power supply but the load caused by the overdischarge, by installing a means that monitors the input power supply given to the load from the internal power supply during the service interruption of a commercial power supply. CONSTITUTION:A commercial power supply AC is converted to a DC power supply voltage by the rectifying/smoothing function provided to a charger 1. At the same time, stabilization is ensured by a stabilizing circuit 7 for the converted voltage. This stabilized voltage is supplied to a load 8 in the form of the prescribed input voltage. The output voltage given from the charger 1 is monitored by an output voltage monitor circuit 3, and at the same time an internal power supply 2 is charged to the voltage value within a prescribed range. When the power supply AC has a service interruption, no prescribed voltage is delivered out of the output of the charger 1 any more. As a result, the output of the charger 1 becomes lower than the potential of the output of the power supply 2. In other words, the input power supply reaction pressure is automatically supplied to the load 8 from the power supply 2. When the power supply AC is recovered, a control part 4 detects this to turn on a transistor Q1. |
