| 摘要 |
<p>PURPOSE:To prevent destruction of stored data in a volatile memory by detecting consumption of a main battery by a detecting circuit to automatically switch the main battery to an auxiliary battery so that the operating voltage is supplied to the volatile memory from the auxiliary battery. CONSTITUTION:A volatile semiconductor memory 1 like a C-MOS memory and a main battery 2 and an auxiliary battery 3 from which the operating voltage is supplied to the memory 1 are provided. When it is detected by a battery consumption detecting circuit 4 that the output voltage of the main battery 2 is lower than a prescribed level, the main battery is switched to the auxiliary battery 3 by a changeover switch circuit 6 in accordance with the control signal from the detecting circuit 4, and the output voltage of the auxiliary battery 3 is supplied to the memory 1. Simultaneously, it is informed by an alarm device 5 that replacement of the main battery 2 is necessary. Thus, data destruction due to consumption of the incorporated battery is prevented.</p> |
