| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a power-on reset circuit which can accurately generate a reset signal even in the case of a momentary break wherein source voltage is momentarily cut off and is recovered immediately. SOLUTION: The power-on reset circuit is composed of a switch circuit 10 and a charging circuit 11 which charges the power-on reset circuit with a delay behind the rise of source voltage, a 1st discharging circuit 12 which discharges electric charges accumulated in the circuit part when the source voltage drops, a waveform shaping circuit 13 which detects the voltage of the charging circuit being above a certain constant level and generates a reset signal or reset undoing signal, and a 2nd discharging circuit 14 which raises the ground level of the waveform shaping circuit by the threshold voltage of a MOS transistor. Consequently, when the source voltage drops or is cut off, the output signal level also transits with voltage decrease so momentary variation in source voltage can be dealt with adequately.</p> |
