| 摘要 |
<p>PURPOSE:To prevent the generation of a fault (latchup) at the restoration of power failure by allowing a relay to monitor normally the power feeding state of a DC voltage and allowing the relay to be changed over automatically to the power feeding from an auxiliary power supply to a volatile storage device if the power supply is stopped. CONSTITUTION:When a DC voltage V0 is supplied from an external power supply, the relay A is activated and the DC voltage V0 regulated to a prescribed voltage by a constant voltage diode ZD is fed to the volatile storage device via a diode DO as a DC voltage V2. Further, a DC voltage V1 is fed to other circuit via a contact a2. If the supply of the DC voltage V0 from the external power supply is stopped because of power failure or the like, the relay A is restored, the contact a1 is made conductive and a contact a2 is blocked. As a result, a DC voltage V2 to the volatile storage device is fed immediately from the auxiliary power supply BO via the contact a1 and a diode D4. When the external power supply is restored, the power supply from the auxiliary power supply BO is blocked.</p> |
