| 摘要 |
PURPOSE:To reset assuredly a microcomputer despite a short break of power supply and a reduction of power supply voltage, by detecting both a short break of power supply and a drop of the power supply less than the working level. CONSTITUTION:When a switch 7 is turned on, a transistor TR11 is turned on. As a result, the base potential of a TR12 is set substantially at 0 and therefore the TR12 is kept off. The TR11 is kept on for a fixed time decided by a capacitor 17 and resistances 13, 14 and 15 and supplies the reset voltage VR to a reset terminal 5 of a microcomputer 1. The TR11 is turned off after a fixed period, and the TR12 is turned on to set the VR at 0. When a power supply has a short break, the electric charge of the capacitor 17 is discharged. Then the power supply is turned on again, and the voltage VR is applied to the terminal 5 in the same way as mentioned above. Thus the computer 1 is reset. |
