| 摘要 |
PURPOSE:To prevent the malfunction of microprocessor, by turning on and off the clock operation in response to the power supply voltage variation. CONSTITUTION:When rated voltage is fed between the power supply terminals of the microprocessor 1, and when the voltage at the junction point B of the resistance R4 and the Zener diode 9 is taken more than the Zener voltage, breakdown current flows to the Zener diode 9. In this case, the voltage at the junction point A between the resistances R1 and R2 is determined with the value of voltage dividing ratio of the resistances R1 and R2. If this value is set so that no forward current flows to the diode 8, the impedance Z viewed from the oscillator is very high. When the voltage between the power supply terminals is lowered, the Zener diode 9 is non- conductive and the potential at point B is increased, thereby flowing current to the diode 8 and lowering the impedance Z. Thus, the clock oscillator is stopped and the processor 1 interrupts the execution. |
