| 摘要 |
PURPOSE:To apply a reset action when a program has a runaway and to improve the stability in case the desired level is outside an allowance range for the voltage obtained from the power supply voltage with the ON/OFF control of two output ports of a microprocessor. CONSTITUTION:If a program has a runway during execution, the gate ON/OFF action is not executed any more for a series of output ports 21 and 22. Then the electric charge of a capacitor 2 is continuously discharged or charged, and therefore the potential of a point A rises or falls. The 1st and 2nd comparators 3 and 4 compare the voltage level of the point A with the lower and upper limit levels in a prescribed allowance voltage range to detect the runaway. Then a reset is applied. The output voltage of an inverter 7 is set at a low level when the program execution is executed. Therefore no reset is applied even though the potential of the point A is outside an allowance range. Thus a malfunction is prevented. |
