| 摘要 |
<p>PURPOSE:To back up the voltage drop of a main power supply with use of an auxiliary power supply of a small capacity by quickly dropping the levels of all input signals of a control circuit consisting of a CMOS when the voltage of the main power supply drops. CONSTITUTION:A power supply monitor means 3 detects that the voltage of a main power supply 21 drops down to a prescribed level and changes quickly its output to a low level from a high level. While an AND means 4 supplies the AND of al input signals supplied to a control circuit 1 of a CMOS and the output of the means 3 to the circuit 1. Thus all input signals of the circuit 1 are quickly change to low levels from high levels when the voltage of the power supply 21 drops. As a result, the power supply current consumed by the circuit 1 can be reduced and therefore the capacity and the scale of an auxiliary power supply are also reduced. Then the power supply 22 of a small capacity can back up the voltage drop of the power supply 21.</p> |
