| 摘要 |
<p>PURPOSE:To surely decide memory backup by providing a deciding means detecting an auxiliary power voltage when the supply of a voltage from a main power source is restarted, and deciding whether the auxiliary power source voltage is in a state where it holds data in the memory or not. CONSTITUTION:When the main power source voltage Vm is supplied from the power source terminal 1 when the supply of the voltage from the main power source is restarted a comparator 10 compares the voltage Vs of an auxiliary power source 9 with a reference voltage Vr. In the case of Vs>Vr, the deciding signal K of an H-level is transmitted to a system-side from a signal output terminal 11. In the case of Vs<Vr, the signal K is set to an L-level. The comparator 10 outputs a control signal C1 when a judgement processing terminates, closes a switch 13 through a switch control circuit 12 and the main power source Vm is supplied to a memory selection circuit 4, a memory 6 and the auxiliary power source 9. When the signal K is at the H-level, the system-side judges that data in the memory 6 is backed up and said data is used again.</p> |
