| 摘要 |
<p>PURPOSE:To improve the reliability of a microcomputer system by restarting automatically the system operation as long as the power supply voltage drops less than a prescribed level owing to an instantaneous service interruption of the power supply, etc., is reset to its original level within a prescribed period of time. CONSTITUTION:The DC power supply voltage VC supplied to a microcomputer system is impressed on a voltage detecting circuit 2. The circuit 2 transmits a signal that is changed to logical L from a logical H to an output terminal 3 when the voltage VC drops less than the voltage V1 and then to an output terminal 4 when the VC drops less than the voltage V2 respectively (V1>V2). The output of the terminal 3 is supplied to a data bus of a CPU and a terminal NMI via a buffer circuit 5 and a flip-flop circuit 6 respectively. While the output of the terminal 4 is supplied to a reset terminal of the CPU via inverter circuits 7 and 8, etc. Thus the operation can be restarted automatically without stopping working of the microcomputer system as long as the dropped voltage VC is reset to its original level within a prescribed period of time.</p> |
