| 摘要 |
<p>PURPOSE:To protect the data stored in a microprocessor with use of a back-up mechanism of a small capacity at a service interruption or the cut-off of a power supply by setting the microprocessor in a stop mode when the voltage value of power supplied to the microprocessor drops down to a level near the voltage which secures the working of the microprocessor. CONSTITUTION:A microprocessor 1 is set in a stop mode when the value of the voltage detected by a voltage detecting circuit 16 which detects the voltage of power supplied to the microprocessor 1 drops down to a level near the voltage that secures the working of the microprocessor 1. Therefore the working of the microprocessor 1 is stopped before the power supply voltage drops and the microprocessor 1 becomes inactive. Then a volatile memory RAM 2 is driven with preference and the data can be protected in the RAM 2. In this case, the actions of other functions are partly stopped for reduction of the power consumption. As a result, a back-up operation is secured for a long period of time despite the reduction of capacity of a back-up mechanism.</p> |
