| 摘要 |
<p>PURPOSE:To prevent important data stored in a memory from being lost by detecting the consumption of the power source of a battery for backup by attaching a voltage detection circuit for a semiconductor memory and an alarm circuit for charging on the power source of the memory. CONSTITUTION:When an AC power source is disconnected, a charge type battery 4 supplies a DC power source to the semiconductor memory 3. At this time, no DC current flows out to a DC power source circuit 1 since a back flow prevention circuit 2 is interposed between the charge type battery 4 and the DC power source circuit 1. The voltage of the charge type battery 4 is always monitored by a voltage detection circuit 5, and when the voltage decreases to a a charge starting voltage set in advance, the voltage detection circuit 5 informs the fact to the alarm circuit 6. The alarm circuit 6 consists of a light emitting diode or a piezoelectric buzzer, or both of them, and an alarm to inform the necessity of charging is issued by flashing the light emitting diode, etc.</p> |
