| 摘要 |
PURPOSE:To obtain an initializing signal forming circuit suitable for an IC, by forming a minute-capacity capacitor internally and controlling the charging of the capacitor by a switching element which is controlled by the amplitude of oscillation. CONSTITUTION:When several hundred ms elapse after power-on, the oscillation of an oscillating circuit (consisting of Xtal, G1 and R) which becomes the steady oscillation state after the elapse of a certain time from power-on is increased gradually, and the output becomes L when the oscillation exceeds the threshold level of an inverter G2. The first FETP1 is turned on, and a capacitor C is charged with a prescribed time constant, and a voltage Vc of the capacitor C rises; and when it exceeds the threshold level of an inverter G5, a set signal becomes L to make a reset signal effective, and an initializing signal In is changed from H to L to terminate the initialization. Consequently, a CR time constant circuit for initialization is unnecessary in the external of the IC, and the reliability is improved considerably. |
