| 摘要 |
<p>PURPOSE:To detect a service interruption with high reliability by setting a power supply voltage detecting circuit in a parallel to a circuit which reduces the level of the voltage supplied to a semiconductor element by means of a diode and extracts the malfunction signal delivered from the semiconductor element before a logic circuit has a malfunction. CONSTITUTION:A logic element 3 uses an element consisting of a semiconductor and receives the supply of the voltage lower than the voltage of a power supply 1 by the voltage drop caused by a diode 2. When the output voltage of the power supply 1 drops slowly, the element 3 has the malfunction and delivers malfunction signal to a register 9 in the form of pulses. The register 9 holds the received signal and sends it to a logic circuit 10. Thus the working of the circuit 10 is stopped. In this case, the output voltage of the power supply 1 is higher than the voltage which cause the malfunction of the circuit 10 by the voltage drop of the diode 2. While the element 3 is unable to deliver any malfunction signal in case the output voltage of the power supply 1 has a sudden drop. Therefore a comparator 8 detects the drop of the voltage and delivers a service interruption signal.</p> |
