| 摘要 |
<p>PURPOSE:To prevent securely microcomputer COM from malfunctioning when a voltage is unstable, by applying a prescribed resetting voltage to COM before the voltage supplied to COM enters into the unstable operation region of COM. CONSTITUTION:With a power switch turned on, a rectifying-smoothing capacitor is charged and as the voltage at DC voltage terminal DC rises, capacitor C2 is charged to input the voltage between the capacitor C2 and resistance R7 to reset terminal IR of COM. When the voltage at terminal IR rises up to a reset level, COM is reset and set in its initial state and its operation is stopped until the reset input is released. The voltage at terminal DC is placed in a prescribed stable state and then the voltage at terminal IR drops below a prescribed level, releasing the reset state of COM. With the power switch turned off, the smoothing capacitor is discharged to reduce the voltage at terminal DC and before it drops below the stable operating voltage of COM, Zener diode ZD2 is turned off to turn on transistor Q4. Thus, C2 is discharged to apply a resetting voltage to terminal IR, stopping the operation of COM.</p> |
